Types of Placer Wash Plants

Types of Placer Wash Plants

There are many different types of washplants on the market today. The one thing that they all have in common is that everyone says theirs is the best! We’re not setting out to prove which plant is the best, this article will explore different types of plants and their strengths and weaknesses. Different plants are suitable for different conditions. There is no one size fits all solution.

There are 4 main components to a wash plant: Scrubber, Concentrator, Feed System, and Carrier. While no two wash plants are identical they all involve a combination of these 4 components.

Take a typical trommel plant that you would find in BC or the Yukon for example. You’ll have a hopper that is fed by an excavator, a trommel that feeds a sluice box and it’s mounted on skids.

Wash Plant Components Placer

Scrubbers

The scrubber is the component of a wash plant that separates raw material and prepares it for concentration. The scrubber will remove large rocks and break down chunks of clay and packed sand. Most scrubber systems use water jets to wash the gravel to remove the fine gold that is attached to the cobbles.

The sand and clay that adheres to pebbles and rocks has been shown to have much higher gold content than the gravel as a whole. For that reason, it is important to wash your material well so that gold can be captured in the concentrator.

The scrubber has three main functions:

  • Separate large cobbles and boulders from the feed gravel
  • Wash the cobbles and gravel
  • Break up clods of agglomerated material

The five categories of scrubbers in use today are the Screen Deck, Trommel, Reverse Trommel, Derocker, and Grizzly.

Trommels

Trommels use a rotating drum to agitate the material. Raw gravel is fed at one end and passes over openings in the drum. Rocks that are larger than the openings are disposed of as tailings. The drum is set at a slight angle to allow the tailing rocks to work their way off the end. Trommels do an excellent job of breaking up clay, mud, and compacted gravels.

A trommel is driven by an electric or gasoline-powered motor. The motor spins the drum by either using a long chain with cogs welded around the drum or by wheels that the drum sits on. Most trommels will have a spray bar running inside the drum that sprays high-pressure water on the gravel to aid in removing gold particles from the rocks. The trommel has a lot of moving parts which is one drawback. The more complex a system is, there more potential for failure.

gold trommel yukon

In North America trommels are most often paired with a sluice box that is positioned at a right angle to the drum. A section of openings are positioned above the sluice box with metal screens to allow specific sizes of particles through. Each mine has different requirements for particle sizes depending on the size of gold that exists there. Miner’s typically have openings of 1/2″ or 3/4″, the size of the opening depends on the distribution of gold sizes in the pay gravels.

Trommels can be paired with any type of concentrator, it doesn’t have to be a sluice. Trommels can be any size. They vary from the Gold Cube trommel which is 5” in diameter and 16” long to plants that can run hundreds of yards per hour with diameters of 8 feet or more. Trommels are relatively easy to set up and can handle a wide range of materials. The big advantage that they have over other scrubbers is the ability to break up cemented or compacted material.

Pros Cons
Can handle different kinds of material Mechanically complex, requires maintenance
Can handle high volume Large footprint
Relatively easy setup Burn a lot of fuel
Breaks up clay and compacted gravel Large trommels are difficult to move

Screen Decks

Screen decks use a series of vibrating screens and water jets to wash gravel and separate large rocks. Each deck is mounted on an angle and suspended by springs and caused to vibrate by mechanical means. There can be multiple decks used or just one.

Like a trommel, screen decks are fed at one end and allow oversize material to fall off the other end. There are perforations in between which allow material to fall through to the lower section. The vibration is caused by the rotation of an unbalanced weight called an “exciter”. That is actually the same thing that causes your cell phone or an Xbox controller to vibrate just on a much larger scale. The exciter is driven by a gas or electric motor. Some smaller models such as the Goldfield Prospector drive the exciter by a pelton wheel using water power alone and no motor.

Klondike Wash Plant

A series of high-pressure water jets are used to wash material as it vibrates. Screen decks allow for well-positioned water jets to be put in place for thorough washing of gravels and rocks. There are a variety of screen options varying from woven wire, to punch plates and rubber or plastic perforated material. Screen sizes vary depending on the gold distribution and material being processed, customization of screen sizes is easy to achieve.

Screen decks can accomplish very high production in the right materials. Some of the largest wash plants in the world are using screen decks for that reason. Unlike a trommel, screen decks do not handle clay or compacted material very well. It tends to bounce off the screens and roll off the end. Despite the violent nature of vibrating beds the screen deck is a relatively simple machine and does not require a lot of maintenance. The only part that is mechanically driven is the exciter and there aren’t a lot of moving parts compared to a trommel or a derocker.

Screen decks tend to be quite high off the ground (at least large scale wash plants). They generally require enough of an elevation difference at the site to be able to feed the hopper and allow room for a concentrator below. Some miners use a conveyor system to get around this problem but mobility is not the screen deck’s strong suit. They work best in a stationary position where they will be used for a long period of time.

Goldfield screen deck cariboo

Pros Cons
High volume Struggles with clay and compacted material
Mechanically simple Large footprint
Fuel-efficient Difficult to move
Separation of multiple sizes Slow to set up

Reverse Trommels

There are a few variations of reverse trommels that work a little differently than a basic trommel. A reverse trommel allows heavy material (ie. gold) to exit one end while the large rocks and waste material exit the other. Reverse trommels often have a double tube design with an inner trommel that screens the material while the outer trommel has a screw-like helix that separates the gold.

Reverse Trommel

The trommel is set at the appropriate angle to allow gold to exit one end while water flows over the outer tube. The helix acts in a similar way to a gold wheel, the material of higher density is allowed to work it’s way up the spiral and exit on one end, the less dense material falls out the other.

There are some models with only one opening that kind of resembles a cement mixer. The APT RG-30 for example. They work in a similar way with a helix and a carefully positioned angle and rate of water flow.

Reverse trommels are popular in the mid-sized range from 1 to 10 yard per hour units. There are quite a few on the market. One popular unit is the Mountain Goat Trommel which is a hobby-level clean-up machine. There are large-scale commercial versions and everything in between.

Reverse trommels are interesting machines and work well once they’re set up but they are much more complicated machines than a basic trommel and are finicky to set up. They also require a lot of maintenance. That’s one reason they are mostly on the small-scale side of the industry.

Pros Cons
Can produce very clean concentrate Require a lot of maintenance
Break up clay very well Slow setup
Separation of multiple sizes Complicated machinery, lots of moving parts
Some designs are very compact Not very fuel-efficient

Derockers

Derockers are a neat machine. They use a flexible deck made of long flat slabs with spaces between them. Under the deck is a carriage frame with truck tires that moves back and forth. There is a high-pressure spray system overhead that washes all the material. As the undercarriage moves back and forth it rolls the rocks around on the deck. The water and rolling action work together to wash off the rocks and allow smaller-sized pebbles and material to fall through the openings in the deck slats (usually 2” minus).

yukon derocker plant

Derockers work really well in areas where there are a lot of large rocks and slabs. They are called “de-rockers” after all. They can handle some clay, due to the rolling action they can break it up somewhat. The derocker was invented in the Yukon to deal with gravel deposits that are full of boulders. These machines can easily handle boulders or slabs up to 4 feet in diameter, which would break other types of separation equipment.

Compared to some of the other scrubbers such as screen decks and trommels, the derocker is a complex machine with a lot of moving parts. You have a carriage that takes a beating, the deck has a lot of links to maintain but the derocker frame itself is stationary.

super sluice finger derocker
Super Sluice Derocker in Cariboo, BC

There was a variation of the derocker in the 1980s called the Super Sluice, made by a company called Gold Machines Inc, that used metal fingers instead of the flexible deck. The Super Sluice was very popular for about 10 years in the Cariboo, Klondike and Atlin but over time the complexity of the machine led to frequent breakdowns and they are very few still in use today.

Pros Cons
Handles large boulders and slabs Require a lot of maintenance
Can break up clay and compacted material Complicated machinery, lots of moving parts
Very high production with the right material Require a lot of water and power to run
Quick setup, easy to feed No adjustment for screening options

Grizzly

Some wash plants don’t have a mechanical separation system at all, some use a simple grizzly. A grizzly consists of vertical bars with spacing to allow the size of material you want to pass through. The grizzly is set on an angle such that the larger rocks will roll off and the stuff that fits through the bars will pass through.

Highbankers and small test plants use a grizzly. Production is slow and they often require manual intervention to clear the large material that collects below. Grizzlys are often incorporated into other separation equipment such as screen decks and trommels.

Pros Cons
No moving parts, no breakdowns Slow production
No motors needed No ability to clear tailings
Easy to move, no setup required Screened material is still coarse
Easy to change for different size of gravel

Concentrators

The concentrator is the heart of a washplant. It’s the part of the wash plant that catches the gold and other dense material.

Placer concentrators all use gravity and inertia to separate material based on density. Gold is very dense, it has a density of 19,300 kg/m³. That means that one cubic meter of gold would weigh 19,300 kilograms (19.3 metric tons). In contrast, the typical gangue minerals such as quartz sand have a density of 2,700 kg/m³ and the black sands have a density of about 5,200 kg/m³.

All concentrating methods depend on this principle, except for the use of mercury but that’s not used in large-scale placer mining.

The Sluice Box

In North America, the sluice is the most common concentrator on commercial placer gold wash plants. The sluice box was developed during the California gold rush around in 1849. The first sluices were called Long Toms. Early sluice boxes consisted of long wooden boxes with wooden riffles and moss or burlap to line the bottom. The primitive long toms saved a ton of labour but miners at that time did not have a pre-scrubber and had to pick all the rocks out by hand and pan all the concentrates.

Modern sluices haven’t changed that much from the original design. We use metal now and have scientific studies to analyze the optimal riffle designs and matting but the concept is exactly the same.

Sluices work by creating a vortex behind the riffles. As the gravel/water slurry flows over the riffle it creates an eddy current as it rolls back on the riffle. The eddy causes the water to momentarily lose inertia and it can no longer carry the dense sediment. Dense material is held in the riffle as long as the water is flowing. Once the water stops, the suspended material is released from the riffles, that’s why it’s not good to stop and start a sluice box.

Sluice Riffles gold

There are a variety of riffles in use today but they all work the same way. There have been some excellent studies on different riffle designs and matting.

  • A study of the fine gold recovery of selected sluice box configurations, Jamie Hamilton at UBC: download PDF
  • Placer Gold Recovery Research by Rany Clarkson of New Era Engineering: download PDF

Studies show which riffle designs work the best, what spacing between riffles is optimal and what angle to run at, typically 1.5 to 2.5 inches/foot of sluice run.

There are several different types of riffles in use today. The Hungarian riffle and expanded metal are most common in commercial sluicing operations. Miners in New Zealand developed the hydraulic riffle in the 90’s that allows water to inject under the riffle which keeps them from packing. It’s similar to the way that the Knelson concentrator uses a fluidized bed, more on that later in this article.

Some modern designs have abandoned riffles altogether and use a drop riffle or vortex such as the Devin Sluice or Dream Mat. These vortex systems catch gold in spirals carved into the matting or machined into aluminum sheets. Vortex riffles and matting have the advantage of quick clean-ups but they tend to work better on small-scale operations and clean-up sluices.

Devin Riffle
Devin Vortex Riffles

Different types of matting are used to catch fine gold. Miner’s moss is a typical matting that is made of a synthetic material with lots of loops to catch gold. Miner’s moss is kind of like a thick version of the soft side of velcro or thick carpet. Actual carpet is used in some cases as well. There are lots of high tech rubber designs on the market such as Gold Cube matting, Gold Hog, Dream Mat and many other designs. Some matting is easier to clean up than others but they all catch gold.

Other variations on the sluice include the live bottom and oscillating sluices. The live bottom box works really well. The live bottom box uses a thick rubber sheet on the bottom of the sluice box and has mechanized rollers that sort of massage the rubber moving it up and down. Similar to the rollers in a massage chair. That keeps the material from packing up and keeps the gold at the bottom.

Sluice boxes can handle huge scale production, they can be made very large and multiple sluices can be run together to handle even higher production. The largest wash plants in the world run multiple sluices. All sluices require careful setup and lots of tweaking to make sure they’re catching all the gold. Sluice riffles will eventually become packed with black sand and can no longer catch gold, for this reason, a sluice must be cleaned out regularly.

Large Scale Sluice Plant

Despite the ubiquity of sluices and their simplicity an alarming number of commercial miners are losing fine gold off the end of their sluice. Quality control and testing is essential to make sure that your sluice is operating as it should be. A full-scale sluice can reliably capture gold down to 150 mesh with proper setup.

Sluices have the major disadvantage of slow cleanup times that require a full shutdown. They also lose gold when you start and stop the slurry feed. They are simple and easy to repair in the field though.

Pros Cons
Can handle large volume Proper setup is critical
Simple design, easy to fix in the field Require shut down for cleanup
Modifications and adjustments are easy Large footprint on commercial operations
Require frequent cleanups

Hydrostatic Jigs

Hydrostatic Jigs, often just called “jigs” are very different than a sluice. They use a pulsating water action to separate gold from the lighter gangue materials. Jigs have serval components that work together to separate gold. Typically they have a screen in the upper section which holds a layer of steel balls called “ragging”, usually about 3” thick. Below the screen and ragging is a rubber diaphragm that is moved up and down rapidly by mechanical means producing a vertical pulsing action. The feed material flows over the screen is allowed to settle into the ragging.

Hydrostatic jig diagram gold

The pulsing action in combination with the steel shot allows dense materials to settle to the bottom while lighter material is forced up and carried away by the flow. The action of the jig is based on Stokes Law which determines the rate at which particles fall while suspended in a fluid based on their density. Jigs are usually arranged in a series of cells, each with its own screen and diaphragm. Any number of cells can be used in combination to increase capacity.

The gold is stored in a container in the bottom called a “hutch”. One advantage to this system in commercial operations is that gold nuggets and pickers are not sitting in the open as they would be in a sluice box so it would be difficult for an employee to steal the gold.

Jigs first came into use in placer mining in 1914 in California. They were soon adopted to the large floating dredges that were in use at the time. Jigs had several advantages over sluice boxes. First, they take up much less space, which was important on a floating dredge. Secondly, they can be cleaned out without having to shut down the operation. You simply need to drain out the hutch and you’re back in business.

One of the first jigs used in placer mining was the Pan American Jig wich consisted of two cells. The Pan American model had two 42-inch square cells and could process 20 yards per hour. Multiple units were used in tandem to increase capacity.

Many modern jigs follow the exact same design as the Pan American. Many manufacturers around the world still produce an almost identical machine. There are many variations of jigs today but they allow work on the same principle. Smaller jigs are often used for cleaning concentrates but larger units are also used in full-scale commercial operations.

Pan American Jig
Pan American Jig

Jig Screens

Pros Cons
Clean up without shutting down Initial setup requires lots of tweaking
Small Footprint Rubber diaphragm wears out
Gold stored in safe container Low capacity per cell
Dummy proof once set up Specialised parts required

Centrifugal Concentrator

Centrifugal concentrators are the most efficient method for concentrating placer gold in terms of capturing fine gold and overall revocery. They rely on a rotating drum that resembles a washing machine. The drum spins at high RPM, usually at least 100 RPM, creating a centrifugal force that pushes heavy elements to the outer edge. If you’ve ever ridden the gravitron ride at an amusement park you’ll know firsthand how this works.

In a centrifugal concentrator, the lighter material is allowed to flow over the top of the bowl and is discharged as tailings, the dense material is held in riffles and retrieved during cleanup. The principle is similar to a hydrostatic jig except more G forces are applied. At high G forces centrifuges are less sensitive to particle size than other gravity methods (sluice, jig, etc) and as such can retrieve extremely small gold grains down to 400 mesh.

There are four types of centrifugal processors on the market today: the Knudsen Concentrator, Falcon Concentrator, Knelson Concentrator, and the Gold Kacha.

The Knudsen was the first centrifugal concentrator used in placer mining. It was invented by George Knudsen of California and patented in 1942. The Ainlay bowl was patented in 1928 and saw some experiments in placer mining but didn’t take off. The Knudsen bowl is a 12” to 36” diameter bowl mounted on a vertical drive shaft. The bowl is tapered to allow the slurry to rise up the side while the riffles catch the gold. The Knudsen bowl was used all over the world most notably in California, New Zealand and in Africa. The Neffco Bowl is a modern version and is still used today.

The Knelson Concentrator was developed in Burnaby, BC in 1980. The Knelson is a bit more complex than the Knudsen Bowl and runs at a higher RPM. The Knelson concentrator uses a perforated cone and uses pressurized water that forces in from the outside of the bowl. The cone experiences a force of 60G’s while the water pushes against it, the counteracting force acts to keep the heavy particles fluidized allowing a continual replacement of light grains by heavy ones and avoiding the compaction of riffles like you see in a sluice. The Knelson concentrator is very efficient but like all centrifugal concentrators it requires frequent cleanups.

Falcon concentrators are similar to the Knelson. The main difference is the angle of the walls. Both use the same water pressure system that pushes against the centrifugal force creating a fluidized bed. Falcon (now called Sepro Mineral Processing) is based in Langley, BC, and was founded in 1987. It’s interesting that both Knelson and Falcon were developed in Greater Vancouver. Both companies are world leaders in mineral processing technology.

The Gold Kacha (GK) is a really cool system. I was introduced to this device on a recent placer exploration trip to Sierra Leone, Africa. The Gold Kacha was developed in 2005 in South Africa by Appropriate Process Technologies (APT). It’s similar to the Knudson/Neffco bowl but has several advantages. The Gold Kacha can easily process gold down to 450 mesh (30 microns) and the riffles are designed to prevent gold compaction. The GK can run 3-4 cubic yards per hour.

It’s set up in a turnkey package that’s easy to use. The biggest advantage is that the Gold Kacha retails for $1,500 USD. All the other concentrators on this list are at least 4 times that cost but the GK was designed for use in third world Africa to help artisanal miners avoid using mercury.

Gold Kacha PlacerGold Kacha Wash Plant

All centrifugal gold processing machines work well for catching very fine gold, they catch coarse gold too but the fine gold is the challenging part. Centrifugal processors can catch extremely fine gold very well but they require frequent cleanups, usually every hour or so. Some wash plants use multiple centrifuges and are able to isolate them using valves so that while one centrifuge is being cleaned the others are still operational, I think we’ll see more of these systems in years to come.

Pros Cons
Able to retrieve gold < 400 mesh Frequent cleanups are required
Easy to use, no special knowledge required Very expensive (except Gold Kacha)
Low water consumption Low capacity per unit (compared to sluice)
Low power/fuel consumption Requires thorough pre-screening and clean water

Spiral Concentrators

Spiral concentrators are not commonly seen at placer mines these days. They were popular in the 70s and 80s but have fallen out of fashion. They are very commonly used in the beneficiation of heavy mineral sands, chromite, tantalite, iron ores and fine coal.
spiral concentrator gold
Basically, spiral concentration involves a stack of spirals that are fed from the top using a low-pressure slurry pump. The slurry flows down the spirals like a water slide and separates based on density. At the bottom there are splitters that divert the slurry at different points along the radius of the spiral. The outside of the spiral will have the tailings, since they are less dense the spiral action forces them to the outside, the concentrated gold is on the inner radius and the “middlings” are in the middle. The principle is similar to the way that a shaker or wave table separates gold.

Spirals are often run several times so that the middlings can be run again to increase their level of concentration. There are several variations such as the pinched sluice and the Reichert Cone which uses a series of stacked cones instead of spirals. The spirals are usually made of fiberglass and are lightweight and fairly inexpensive. They are able to reliable capture gold from 6 to 200 mesh, some models can catch down to 300 mesh. Placer spiral systems can handle 4-10 yards per hour but can be scaled up with more units.

gold spiral africa

Pros Cons
Able to retrieve gold < 300 mesh Require consistent, laminar flow
Easy to use, no special knowledge required Low capacity per unit (compared to sluice)
Low cost and cheap to operate Requires thorough pre-screening
Low power/fuel consumption

Dry Washers

Gold is found in areas that don’t have water available, such as the desert regions of California, Nevada, Arizona, and Australia. Placer miners came up with a solution for dry washing.

The process works on the principle of winnowing, which uses wind or air to separate dense material from less dense material. The technique has been used for millennia to separate grains from their husks. Dry washers use a short, waterless sluice and pressurized air in combination with vibration. The sluice portion of a dryswasher has a porous bottom, either canvas or a very fine screen, that allows air to pass through. The whole thing is set on a steep angle so that the material can work its way over the riffles. Air blows up from the bottom and provides some buoyancy for lighter material.

drywasher

Small scale dry washers resemble a highbanker with a screen/grizzly on the upper section and a sluice-like screen setup on the bottom. There are hand-operated units using bellows, and gas-powered blowers. Commercial-scale drywasers are somewhat rare but they are used in gold-rich areas of Australia and parts of the United States.

There are no manufacturers that make commercial-scale dry washers. All large scale units are custom made. Most of them are fed by a loader and distribute the material through a screen system into multiple cells of smaller dry washer sluices. Keene is developing a commercial drywasher but it’s not available at this time.

Material to be run in a drywasher must be completely dry, it must contain less than 3% water otherwise it won’t work. The material must also be disintegrated and not clumped together by clay or caliche. Studies show that under ideal conditions a dry washer will have about 15% less recovery than a wet system (ie. sluice).

Pros Cons
Doesn’t require water Lower recovery than wet systems
Can be moved rapidly Makes a lot of dust
Fast cleanup (compared to wet sluice) Frequent cleanups are required

Feed Systems

We’ve covered screening systems and concentrators. The next component of a wash plant is the feed system. Wash plants can be fed in different ways. Some have a hopper that is fed by an excavator or loader, others are fed by a slurry pump or dredge.

Hoppers

The most common feed system on a wash plant is the hopper. The hopper is a large container that is filled with raw gravel and allows it to be dispersed at an even rate. Many hoppers are gravity-fed, they operate in a similar way to an hourglass. They have an inverted pyramid shape and act as a funnel.

Other hoppers have a belt or track in the bottom that manages the feed rate. I’ve seen some cool designs in the Yukon that use a recycled excavator track in the bottom of the hopper to slowly feed a trommel.

The hopper won’t feed itself and must be refilled regularly by an operator. Most operations either use an excavator or a front end loader to keep the hopper full. Some miners use a conveyor belt system in combination with a hopper to maintain an even flow of material.

Pros Cons
Maintain even flow (when not clogged) Large rocks can get stuck
Simple design, not much to break down Requires operator to refill regularly

Bucket Ladder

The bucket ladder is the most efficient system for feeding wash plant. This was the norm on the monster floating dredges that scoured the gold-bearing placers of western North America from the late 1800s till the 1950s. These monster dredges moved ridiculous amounts of gravel, each dredge could efficiently process up to nine tons of gravel per minute, with an average of 20,000 cubic yards per day!

The bucket ladder consists of a boom and a series of metal digging buckets. It’s sort of like a giant chainsaw. The buckets are specially designed with a digging edge and held together with a giant chain. The boom is raised up and down with a gantry winch system. The buckets continually dump material into the scrubber system (trommel, screen deck or any other system that we discussed above).

The depth of the bucket line is limited to the length of the boom. Typical industrial dredges could dig up to 60 feet deep. The buckets are able to dig up soft bedrock but if hard rock is encountered they cannot. The buckets can’t handle large boulders either. The dredge in the video below isn’t at a placer mine but it shows what a modern bucket ladder dredge can do.

Environmental restrictions have made it a lot more difficult to operate a floating plant with a bucket line but some are still in operation today in Europe, Africa, Russia, China, Asia, South America, Mexico and the Yukon. Modern bucket ladder dredges are common in non-placer applications

Pros Cons
Constant supply of material Can’t dig too deep
Huge capacity Massive overhead cost
Excavation and delivery in one step Not very mobile
Few breakdowns Regulatory hurdles

Gravel Pump

One of the most efficient ways to feed a wash plant is with a gavel or slurry pump. There are several large-scale placer mines in Alaska and other parts of the world that mine by hydraulic means using large water monitors. The material is washed into a pit and pumped up to the wash plant using large industrial slurry pumps.

Gravel pumps don’t work in every scenario but if your location is favorable this is a very efficient way to mine. The slurry pump can be unmanned, saving labour costs and allowing workers to focus on other areas of the mine. These pumps are very expensive initially but the savings in operating costs will pay off over time.

There are a lot of mines operating in wet ground in BC and the Yukon and a slurry pump would be an excellent solution. Instead of fighting the groundwater you can use it to your advantage.

Gravel Pumphydraulic Mine Sierra Leone

Pros Cons
Consistent feed of material High initial cost
High capacity Requires careful mine planning
Savings on labour Doesn’t work in every location
Good solution for wet ground Possible regulatory hurdles

Suction Dredge

Suction dredges are similar to a slurry pump set up. A suction dredge uses a venturi to create a vacuum that sucks up gravel and water at the same time. Floating dredges are commonly used in small to mid-scale mining. Floating dredges are classified by the diameter of the suction hose which varies from 3 to 8 inches.

Modern suction dredges first became popular in the 1950s due to the availability of good, portable, centrifugal water pumps and modern diving equipment. Some jurisdictions such as British Columbia and parts of California have banned suction dredging but it is a very efficient method that is used around the world.

There are some very advanced dredge machines on the market today. Large scale operations are using 8-inch and larger suction lines. Some of the most interesting dredge innovations are being developed for use on the Bearing Sea in Alaska. The robot dredge in the picture below is a really cool new technology that uses a remotely operated robot with a cutting head attached to an 8-inch dredge.

Robot Dredge Gold

Not all dredge systems use a floating platform and can be fitted to just about any wash plant. You can get excavator-mounted units up to 12” in diameter that can be used in a regular mining pit. These systems advertise up to 600 cubic yards per hour of production.

Some systems use slurry pumps instead of a venturi in combination with a cutting head. The advent of undersea mining has pushed the envelope on this technology and we’re going to see a lot of advancements in the coming years.

Pros Cons
Consistent feed of material Doesn’t work in every location
Excavation and feed at the same time Possible regulatory hurdles
Can be unmanned

Wash Plant Carriers

This is the part of the washplant that supports the scrubber, concentrator, and feed system.

Stationary Skids

Many large wash plants are mounted on a steel frame welded to metal skids. This system isn’t very mobile. Skid-mounted plants are meant to stay in one place for a long time. When it’s time to move they are pulled by heavy equipment such as bulldozers or large excavators and dragged into position.

Skids are simple and stable but don’t provide a lot of mobility.

Trailer or Frame with Wheels

Small to mid-sized wash plants can be mounted on a trailer or frame with wheels. This provides an easy way to move it around. The trailer will often have a leveling apparatus to stabilize the plant while in use. Not much else to say, it’s a trailer we all know what that is.

Floater Plant

The floater plant, also known as a “Doodlebug” is a very efficient way to mine. The plant can be mounted on pontoons or a barge. Floater plants have the ability to move very rapidly in a pond of their own making. It takes planning to operate efficiently without boxing yourself in but when properly executed a floater setup can move a lot of material quickly.

Any type of scrubber, concentrator, and feed system can be fitted onto a floater.

The large bucket line dredges technically fall into this category but most floaters today use an excavator to dig and pull the barge. For a floater operation to work effectively the ground can’t be too deep. Floaters mine in one continuous direction mining in front of the plant while the tailings are deposited behind. It’s almost like an assembly line approach to placer mining.

Pros Cons
Rapid movement Don’t work in deep ground
Efficient mining and tailings management Require a pond for the plant to float on
Floater Wash Plant Atlin Yukon
Floater Plant in Atlin, BC

A placer wash plant is the sum of its parts. It’s not a trommel, it’s not a sluice, it’s the whole package. There are just about as many combinations as there are miners. Placer miners are always coming up with new innovations to solve problems and mine more efficiently.

There is no one plant that is the best in every situation. They all have their strengths and their weaknesses. The type and size of your gold, the type of gravels you’re dealing with, ground conditions, regulatory environment, available capital, and other factors all work together to determine what type of wash plant is best for your mining operation.

Searching for Ancient Rivers in West Africa

Searching for Ancient Rivers in West Africa

In April 2021 West Coast Placer was hired to assist in exploration for a large-scale alluvial gold project in Sierra Leone, West Africa. This program took place in the Kono region of Sierra Leone which hosts diamonds as well as gold in their placer deposits. It was a great experience and it was really cool to see how they do things in West Africa compared to the West Coast of North America.

seismic bedrock placer sierra Leone

Sierra Leone is famous for its alluvial diamonds. We were working in the Kono district which is where the plot of the movie Blood Diamond took place. The region where Leonardo DiCaprio’s character died at the end (spoiler alert) is not far from the survey area that we were exploring.

Despite extensive diamond mining taking place in the region since the 1930s very little attention had been paid to the alluvial gold deposits. There are a lot of artisanal miners active in the area but their sole focus is diamonds and they often discard the gold that they dig up. That fact surprised me because even in Canada where the average income and standard of living is much, much higher nobody would ever throw gold back into a river. That’s one of many things that’s different in Africa.

alluvial diamonds gold Africa artisanal

The placer deposits in the Kono region are much older than anything in BC or the Yukon. Much of the bedrock is Precambrian (500 million to 4 billion years old) and hasn’t ever been glaciated. By contrast, the rock in BC is less than 200 million years old and has been bulldozed by large glaciers on at least 4 occasions. Despite the differences, some things are the same in pretty much every placer environment. Over time rivers and streams move and leave their gold deposits behind in ancient paleochannels. That’s what we were looking for. Our system is designed to map bedrock depth and show the location of paleochannels.

Ancient Channel Gold Map Africa
Actual Map from a survey in Africa in 2021

Travelling internationally during the covid-19 pandemic is quite an adventure. In April 2021 the vaccines weren’t available yet and travel restrictions were very tough. We had to do lots of covid tests at each leg of the journey and there were a few hiccups. One of our team members wasn’t allowed to board the flight to Belgium from Montreal because his test was taken too far in advance. He had to get another PCR test and catch a flight the next day. On the way back I almost had to stay in a covid hotel, fortunately, the Canadian government honored my essential service exemption.

artisanal mining village sierra leone

It was interesting that Sierra Leone didn’t have a lot of covid restrictions. That’s because three years prior to the breakout of Covid -19 around the world West Africa was center stage to the worst ebola outbreak in history. When covid broke out in 2020 they knew what to do and locked the whole country down with no exceptions. By the time we arrived in 2021 the whole country had a total case count of 80 and zero deaths. With the intense screening protocols for international travellers they were able to keep infection rates to a minimum, something that wealthy western countries weren’t able to do, even with the advent of vaccines.

We spent a few nights in the capital city of Freetown and headed off to Koidu Town to begin our exploration. The bedrock mapping survey covered a large area that was chosen due to the prevalence of artisinal mining and topographic features that favoured the development of paleochannels. We had some knowledge of hard rock gold production in the area and anecdotal evidence from local artisanal placer miners.

excavator placer alluvial west africa
There’s no 6 month wait for permits in Sierra Leone

We had a crew of local laborers which included the son of the Paramount Chief. That was important for public relations since we didn’t speak the local language and it was important to explain to the villagers what we were doing. Having the chief on our side let everyone know that we were working along with local government and not just rolling in to take all the resources for ourselves.

Sierra Leone is ruled by a combination of federal government and chiefdoms. The mining claims are managed by both levels of government in a complex way. Without the support of the chief it would be hard to get the necessary permitting and support of the local community. Luckily for us, the local chief is a miner himself and we got along really well.

The artisanal miners do a lot of the work by hand. They often use gas-powered water pumps similar to what small-scale miners use in Canada. Mostly for dewatering though, they don’t have highbankers like we do back home. In Africa people carry everything on their heads, even the water pumps.

artisanal miner carrying water pump on head

Most of the washing is done by hand using gem screens or large gold pans. The larger operations use a rudimentary hydrostatic jig. There are very few operations using heavy equipment but manpower is readily available in this area.

The local miners have a method of digging shafts that works really well in the clay-rich gravels in that area. They dig a shaft about 1 meter wide and dig out foot holds on the way down. In this way they can reach bedrock in a day or two and get really good samples from the bedrock interface. The company that we were working with hired a large crew of local miners to dig shafts instead of using a drill. The samples were better and expert shaft diggers were more than willing to work for $10 US per day.

shaft made by artisanal miners sierra leone
Shaft made by artisanal miners in Kono region

Getting supplies in a third world country can be an adventure in itself. We tried to bring everything that we needed with us but we counted on procuring some supplies locally. One thing that we need lots of was flagging tape. Since this is a mining area we thought it wouldn’t be too hard to find. It turns out that there is no flagging tape available for sale in the entire city of Koidu. Despite two full-scale kimberlite mines right next to the city. We had to buy fabric ribbon in bright colours and use scissors to cut it in order to mark our lines.

It turned out that the local kids like the fabric just as much as we did since they would come right behind us and pull all the ribbon off the lines as soon as we were done. Sometimes they wouldn’t even wait till we had completed the line which made a few sections really challenging.

Some of the more high tech mining devices in Africa are really cool. The company had some really efficient gold centrifuges for testing the gravels. They’re like a gravity concentrator that you see in North America but made to be economical and easy to deploy. One machine is called the Gold Kacha and works really well.

Gold Kacha Centrifuge Africadiy sluice sierra leone

Centrifuges aren’t commonly used in placer mining in BC and the Yukon but that’s something that we should really consider. The gravity concentrators on the market are expensive in Canada but you can get a Gold Kacha out of South Africa for about the same price ad an average highbanker setup here in BC.

The local gold panning technique is quite different from what I’m used to. They use a large rounded bowl with handles on the sides. There are no riffles and the sides have a very gentle slope. My technique didn’t work to well with their pans. The local technique is to swirl the material in the pan while letting the lighter stuff wash over the sides. One of my crew members demonstrated the technique in the video below.

The bedrock mapping survey was a huge success. We identified a clear paleo-valley and an ancient river channel that spanned several kilometers. Much of the area that we identified with the seismic survey as an ancient channel had never been exploited by artisanal miners.

One great thing about working in Sierra Leone is you don’t need permits as you do in BC. We were able to start digging with an excavator right away. With a combination of bulk sampling with the excavator and teams of local shaft diggers sampling was completed in less than a month. The gold grades within the channel were excellent and alluvial diamonds were also present.

Kono Bedrock Cross Section

Exploring a new area is always a welcome experience. As explorers, we are constantly striving to search different areas and locate mineable gold deposits. This exploration program in West Africa did not disappoint. It was quite a contrast to use the latest technologies in an area where people are still living in mud huts and cooking with charcoal. Some of the ancient techniques used in Sierra Leone are very efficient, such as the shaft digging technique. If we could get hundreds of workers to dig shafts in Canada for $10 per day imagine the ground that could be explored.

We managed to locate a very rich placer deposit containing minable quantities of gold and alluvial diamonds. This project was developed with the support and mutual benefit of the local chiefdom and communities. It was a great experience to share knowledge of different mining and exploration techniques and learn a few new ones as well.

How to Lose Your Shirt in Placer Mining

How to Lose Your Shirt in Placer Mining

What makes placer mining unique is that you have control over your own destiny. The barriers to entry are low and a small group of people can have the opportunity to develop a mine and produce gold on their own terms. You don’t need a corporation and millions of dollars to succeed in placer mining. That freedom is a double-edged sword though. The majority of placer miners bite off more than they can chew and fail miserably.

This article lists some sure-fire methods to lose your shirt in placer mining that apply to large-scale mines and small hand operations alike. By knowing the mistakes that others have made you can avoid making the same mistakes yourself.

Three Placer Wash Plants

Too much equipment, Too soon

There is a lot of equipment available to placer miners these days. A lot of rookie miners will buy way too much equipment before they even get started. That’s a great way to blow your budget without even finding any gold.

The fitness industry relies on this same principle. It doesn’t take much effort to go out and buy a brand new stationary bike but just owning that machine isn’t going to give you abs of steel. Getting in shape takes hard work and dedication. Placer gold exploration works the same way. Some miners seem to think that buying a bigger wash plant, a bigger excavator, or even the latest and greatest highbanker will somehow make gold appear. It’s easy to buy equipment, finding gold is hard.

If you want to blow your whole mining venture in the first season then buy too big of equipment before you’ve even explored your claim. You’ll be part of the illustrious club of would-be miners who failed before they even got started.

We were contacted recently by a miner who wanted to hire West Coast Placer to do some bedrock mapping. The miner had recently purchased a $250,000 wash plant. We asked them where they were mining and they responded, “We’re hoping that you can help us figure that out.” They didn’t even have a claim yet. That is not a recipe for success.

Other miners have spent their money on excavators, loaders, and high-end camp setups but then had nothing left to buy a drill. At different stages of placer exploration you’ll need different equipment. Having a solid plan will help you figure out what is required at each stage.

If you want to be successful explore the claim first and get the gear that you need to work in that specific situation. You don’t need a washplant until you’ve actually mapped out a mineable gold deposit and have a mining plan figured out. Start out with basic tools and expand as needed. During exploration the trick is to gather as much information as possible while spending the least amount of money.

Get hooked on a glory hole

We can all look at other miners who spent three years digging in the same spot totally convinced that it’s going to make them rich. We shake our heads and think of how stupid they are. However, a lot of miners fall into this trap.

What is it about glory holes that suck in the imagination of placer miners? It’s sort of like gold fever. Miner’s get hooked on the belief that one specific spot holds all the gold and that if they can just dig it up they’ll be rich.

This sickness can affect rookies and even some experienced miners. Sometimes it’s driven by a story from the past, or a misinterpretation of a geological feature. Getting hooked on a glory hole is similar to being in a romantic relationship that is totally toxic. All your friends know but you don’t realize it yourself until after the breakup.

This situation can be easily avoided by proper sampling and testing. A whole season’s worth of excavating in the wrong spot ( or multiple seasons for some people) can be avoided with one drill hole. If you are convinced that there is a whole bunch of gold in one spot, and you haven’t tested to confirm, then you have fallen victim to the glory hole trap.

Drink your own Kool-aid

Every placer miner has their reasons for digging and exploring in the spots that they do. Sometimes that’s based on good test results but often it’s based on nothing more than imagination.

Many miners have developed a form of fairy tale in explaining the gold deposits on their claim. The geological, fluvial, and glacial environments that create placer pay streaks are extremely complex. There are entire fields of science that dedicate themselves to understanding these processes. Even an expert geomorphologist can’t walk up to a placer claim and tell you what material has been deposited over the last 4 glacial periods, where the ancient channels are located and what ancient streams used to flow over the mountain range. If you think you know those answers then you are heading down a dangerous path.

I’ve heard a lot of stories from placer miners who seem to know the exact play-by-play movements of glaciers during the last ice age and therefore know exactly where their gold has been accumulated. Obviously, they don’t have reliable knowledge of the geological history of their claim but they have convinced themselves that they do.

Others are convinced that there is a gold source up the mountain and it has puked out placer gold in a specific location that they’re about to mine. All without sampling and mapping out deposits.

It takes massive amounts of time and money to reliably recreate glacial movements. They are extremely complex and hard to trace. There are well-funded research projects that study these kinds of things with teams of experts and even they are not 100% certain.

If you think that you have those answers and haven’t hired expert geomorphologists, drilling companies, and performed large-scale studies to find out, then you’re just fooling yourself.

Truthfully in placer mining, you don’t need to know how the gold got there. All you have to do is test and sample the ground to find out where the gold is right now. Finding mineable placer deposits is hard and there are no shortcuts. There are techniques that work really well but believing in your own fairy tales isn’t going to make the gold appear. It’s much better to assume that you know nothing and explore in a systematic way.

Gold Legend Map BC

Put too much emphasis on stories from the past

Every creek has a success story from the past about an old-timer who pulled out some rich gold from an ambiguous location nearby. They usually go something like this:

“In the 1920’s Johnny Miner pulled out a 30-ounce nugget from somewhere up on that hill over there.”

Other stories involve drifts built by Chinese miners in the 1890s or a rich mine that was wiped out by a wildfire never to be found again. They have a lot in common with urban legends with the right mix of potential gain and just enough details to keep you interested.

There are lots of stories like this and a lot of them are true. Being a placer miner in the 21st century involves being a little bit of a historian as well as an explorer. After all, there are pretty much zero creeks in the world that haven’t had a pan dipped in them at least once before.

There are several issues with historical information that sometimes slip through our radar. We all know that clickbait stories on the internet are probably exaggerated to capture our attention. That phenomenon is not a new invention. Speculation and hype have always been part of mining. It was probably even worse during the gold rush periods of the late 1800s. Testing techniques are not standardized either. Even if a story is meant to be factual the miner might not have had a reliable technique to test his grades. You could fall victim to second-hand confirmation bias from 100 years ago and not even know it.

Whether these stories are true or not you still need to do your own testing. Reliable historical information can be an excellent starting point but it must be taken with a grain of salt. If you have truly uncovered some historical information that provides evidence for a forgotten placer deposit then start testing that area. Remain objective and if the test results don’t show what you’re expecting then move on.

Far too many miners have spent their time and budget blindly searching for a rich paystreak that was mentioned decades ago. I personally know miners who have spent hundreds of thousands of dollars searching based on three sentences of historical information.

Keep an open mind and let the evidence guide you. It’s important to know when enough is enough.

Insufficient sampling

We’ve all heard the old adage that in real estate that the three most important things are location, location, location. In the world of placer mining, the three most important words are sampling, sampling, sampling.

Our Auger Drill

This is the single most important aspect of placer mining and exploration. Miners of all sizes have lost money and often their entire budget due to poor sampling. There are lots of reasons why miners forgo proper sampling. It costs money, it takes time away from mining, maybe they don’t know how to sample properly in the first place.

Sampling will make or break your placer operation. It must be done over a broad area and in a way that won’t fool the person doing it. The quality of sampling is just as important as the quantity.

For example, it is critically important to measure the volume of each sample accurately otherwise the grade calculations will be totally wrong. Say you sampled half an excavator bucket and found 3 grams of gold. Is that 3 grams per yard? Or half of that? It makes a big difference. Let’s say you’re using 5-gallon pails. Were they all full when you ran the sample? Half-full? Three quarters? Your grade calculations will change dramatically based on the volume.

Bigger samples are always better but there is a trade-off between lots of small samples and only a handful of big ones. Each situation and budget will call for variations in the sampling plan. You want to have enough locations tested to be confident that you understand the size and distribution of your pay streak while getting reliable results in each sample.

It’s important to test areas outside of the location where you think the best gold is. That means testing every depth interval from surface to bedrock as well as testing ground whether you think it’s a location that you can mine or not. Many miners have missed out on unbelievable pay because they only tested areas that they thought were favorable for mining. Here’s a tip, every spot is favorable for mining if the gold grades are high enough.

Placer exploration is a little bit like the board game Battleship, where you have to shoot missiles on a blind grid to sink your opponent’s ships. You start out knowing nothing but over time you gain evidence of where things are located, in this case gold instead of toy battleships. The same systematic approach will lead you to win Battleship as it will to mine a profitable placer deposit.

If you think you’ve done enough sampling, you haven’t. If you start washing gravels before you have sampled a broad area with verifiable tests you are guaranteed to lose your shirt.

Before you start mining make sure that you know the depth, location, and the grades of your pay gravels. There are a lot of opinions on what the proper way to sample is. The important thing is to be thorough and be consistent.

Get a Partner

Many great placer mining operations have met their demise due to disagreements between partners. It always sounds like a good idea at the time but partnerships fail for a variety of reasons. Most often financial disagreements.

Howard from the great mining classic, The Treasure of the Sierra Madre said it best,

“Ah, as long as there’s no find, the noble brotherhood will last but when the piles of gold begin to grow… that’s when the trouble starts.”

Gold does funny things to some people. Even people that you wouldn’t expect. There’s something about the yellow metal that affects us deep inside. It’s not just the financial value either. Silver, copper, uranium, platinum, and numerous other metals are mined in similar ways but people don’t get as emotionally attached to any of those things. The only other mineral that affects people in a similar way is diamonds.

Gold fever has existed as long as people have been mining. The primary reason that the Spanish explorers stumbled upon North America was the search for gold. Christopher Columbus wasn’t looking for America, his sole purpose was to find Cipangu, the island of “endless gold.” The Spanish explorers famously ravished and betrayed civilizations in the Americas to steal their gold. The betrayal met its climax in 1532 when Francisco Pizarro famously betrayed the Inca ruler Atahualpa.

Partnerships fail for many reasons but greed is often the primary factor. Sometimes personal finances fall apart, a partner gets divorced, falls behind on truck payments, anything can happen. A lot of placer mines that have done everything right and developed great gold deposits have fallen apart due to disagreements between partners.

Gold mining partnerships always start out with the best intentions but humans are complex and things can change. If you’re considering a partnership make sure the person or people that you’re going to join forces with are going to stick it out for the long haul. Make sure you have a solid contract in place that has been verified by a lawyer or notary.

They say a business partnership is like a marriage. You want to be careful who you’re going to bed with.

Mining Partner BC Gold Placer

At West Coast Placer we provide exploration services to placer miners of all sizes. We’ve seen a lot of successful operations and have helped miners develop their properties into profitable mines. We’ve also seen a lot of ventures fail miserably. There are some practices that are guaranteed to lead to failure and yet rookie and experienced miners alike make these mistakes over and over again. Hopefully these tips will help you stay successful in placer mining and keep you from losing your shirt.

Deep Dive into Dowsing

Deep Dive into Dowsing

As prospectors, we have a deep connection to the past. We live in a world where technology has advanced to an amazing level. High tech devices that could only be imagined by science fiction authors a few decades ago are part of our everyday lives. Despite the current state of technological advancement, there is still no surefire way to detect unexplored gold deposits. Our pursuit of the yellow metal leaves no stone unturned. A good prospector will employ every tool at their disposal to get even the slightest edge in locating a gold deposit.

We look to the prospectors of the past and admire their ability to locate gold deposits with nothing more than their own ingenuity and a sense of adventure. Some techniques are no longer used and some haven’t changed for centuries. Dowsing fits somewhere in between. It’s always been a mystery. Nobody can explain how it works but many swear on their mother’s grave that it does.

Dowsing refers to the practice of using a forked stick, metal rod, pendulum, or similar device to locate underground water, minerals, or other hidden or lost substances, and has been a subject of discussion and controversy for
hundreds, if not thousands, of years. The practice is also called divining or witching. There is a history of mysticism, magic, and supernatural beliefs associated with the divining rod that dates back over 8,000 years.

In the Tassili Caves of northern Africa, an 8,000-year-old cave painting depicts a man holding a forked stick, apparently using it to search for water.
Divining rods were used by the Scythians, Persians, and Medes. The practice was used by Bavarian miners in the early 1500s and spread throughout Europe as their deep mining skills were highly sought after. Check out our article on Free Miners for a bit more info on that.

dowsing branch

Controversy on the subject goes back to before medieval times. In 1518 Martin Luther listed the use of the divining rod as an act that broke the first commandment under the assumption that dowsing is in league with witchcraft. One of the most important books on mining during that period called “De Re Metallica”, published in 1556, describes the practice in this excerpt:

There are many great contentions between miners concerning the forked twig, for some say that it is of the greatest use in discovering veins, and others deny it. Some of those who manipulate and use the twig, first cut a fork from a hazel bush with a knife, for this bush they consider more efficacious than any other for revealing the veins, especially if the hazel bush grows above a vein.

Others use a different kind of twig for each metal when they are seeking to discover the veins, for they employ hazel twigs for veins of silver; ash twigs for copper; pitch pine for lead and especially tin, and rods made of iron and steel for gold. All alike grasp the forks of the twig with their hands, clenching their fists, it being necessary that the clenched fingers should be held toward the sky in order that the twig should be raised at that end where the two branches meet. Then they wander hither and thither at random through mountainous regions.

It is said that the moment they place their feet on a vein the twig immediately turns and twists, and so by its action discloses the vein; when they move their feet again and go away from that spot the twig becomes once more immobile.

Nevertheless, these things give rise to the faith among common miners that veins are discovered by the use of twigs, because whilst using these they do accidentally discover some; but it more often happens that they lose their labour, and although they might discover a vein, they become none the less exhausted in digging useless trenches than do the miners who prospect in an unfortunate locality.

Therefore a miner, since we think he ought to be a good and serious man, should not make use of an enchanted twig, because if he is prudent and skilled in the natural signs, he understands that a forked stick is of no use to him, for as I have said before, there are the natural indications of the veins which he can see for himself without the help of twigs.

There are variations on the construction of dowsing rods. The original technique consists of using a forked branch cut from a live tree, any tree will work but sticks from willows, witch hazel, and various fruit and nut trees seem to be the most popular. You grasp the ends of the “Y “in your hands with your palms facing upwards. The technique is to walk around and as you approach the target (ground water, gold deplost, etc) the rod will bend towards the ground.

Modern dowsers prefer to use metal rods. A modern dowsing rod consists of two metal rods created from sixteen inch long steel acetylene welding rods with a 90 degree bend forming a handle on each (also known as L-rods). The latest innovation uses ball bearings in the handle to allow the rod to move freely. The modern divining rods don’t bend towards the ground, the technique is to allow the rods to either cross or reach the operator’s chest or point in certain directions.

There are people claiming to be able to conduct long-range dowsing from distances of 100s of meters up to thousands of kilometers away. Some even claim to be able to dowse using a map from the other side of the world.

Dowsers claim to be able to find all sorts of things ranging from water to gold and even your lost car keys. Dowsing for water is the most common. There are quite a few practitioners of water dowsing that do so as a career. The American Society of Dowsers currently has over 2000 members.

Personal Accounts

In the summer of 2020 I had the opportunity to try dowsing myself. A friend of mine had some dowsing rods and we gave it a try while exploring his claim. He told me that you need to visualize the thing that you’re looking for. In this case we were exploring for a hidden paleochannel.

I held the rods horizontally so that they were able to move freely and walked in a straight line while keeping the idea of a channel in my head. At one spot I was surprised to feel the rods moving without my control and they did cross in front of me. It was a cool feeling and did seem supernatural. We marked the spot using a pin flag. My friend continued over a larger area and we mapped several spots where he felt the rods cross. The results didn’t match up to our seismic survey but he will be testing the area with his excavator next summer.

My personal account was by no means a conclusive test. It certainly piqued my curiosity though.

I know several professionals that occasionally use the technique to locate underground utilities such as water lines and electrical lines. They swear that it works, they don’t know how or why but swear that it does. Several utility companies in Canada do use divining rods occasionally.

Ball Bearing Dowsing Rods
Modern Ball Bearing Dowsing Rods

Long Range Locators

There are even electronic devices that claim to extend the dowsing signal for great distances. These devices are called Long Range Locators (LRLs).

There is quite a range of LRLs on the market, they range from devices that look like a ray gun to “signal generators”, “oscillators”, “harmonic molecular resonators”, or other scientific-sounding names. The world of LRLs is very murky. The majority of LRLs are fake and many manufacturers have been charged with fraud.

One such device called the Omni-Range Master retails for $2,885 USD and makes the following claim:

The signal line from the Omni-Range Master can scan an area of at least 64 square miles and determine if any of the sought-after mineral is present within 15 minutes of the start of operation

It also claims to have “Accuracy of 1/32 of an inch from 50 feet to over 8 miles”. Wow, it would be pretty cool if that actually worked!

Omni Range Master Dowsing
Omni Range Master

Credit for the above photo goes to Carl at geotech1.com. He’s done a lot of research and testing on LRLs. Check out his site for some surprises on some of the most popular long-range locator products on the market.

The Omni-Range Master is a favorite among dowsing and LRL enthusiasts even though it doesn’t actually do anything.

The manufacturer supplies a list of frequencies to locate various substances and items such as:

  • Diamonds – 12.835 Khz
  • Gold – 3.025 Khz
  • Titanium – 13.385 Khz
  • “Prehistoric Rex” bones – 15.367 Khz
  • Paper money ($100) – 9.41 Khz
  • Paper money ($20) – 12.77 Khz

It’s interesting that it mentions bones of a non-existent dinosaur which would be made up of a complex mix of molecules. It’s also strange that it has two different frequencies for paper money and that it lists paper money at all.

This device uses a standard waveform generator (chip that produces an electrical current in a variety of voltages and frequencies). You then plug electrodes into the ground and the idea is that the device will induce “molecular resonance” in the surrounding area and create “signal lines” that you can follow with dowsing rods.

The device uses a 12V power supply and does not transmit enough power to do anything productive. I suspect that believers in “signal lines” and LRLs believe that a very low voltage can be amplified by a form of harmonic resonance but there is absolutely zero evidence for that.

At face value, the concept of “frequencies” and electrodes in the ground is similar to some geophysical techniques such as Induced Polarization (IP) and Resistivity that are commonly used. IP uses 25,000 volts and very specialized recording equipment. It also involves a comprehensive data processing technique. IP can detect conductive ore bodies if they are big enough but even that advanced geophysical technique won’t show you exactly where gold is (or dinosaur bones).

Explanations of the Phenomenon

Proponents of the dowsing technique have a variety of explanations of the mechanics behind the phenomena. One person on a prospecting forum recently claimed “The rods simply extend your personal magnetic field..which, in turn responds to, and interacts with vibrational frequencies of the Earth.”

Some claim that there is psychic energy involved while others say it has something to do with the solar cycle and charged particles from the sun. There are just about as many explanations as there are practitioners.

Molecular Resonance Gold Dowsing

A recently published book, “The Art of Dowsing: Separating Science from Superstition” by Michael Fercik, tried to explain dowsing in scientific terms. Here’s a quote from the book:

The hands-on dowsing practices are absolutely 100 percent correct, but the dowsing theory could be slightly off here or there. I expressed in wording to the best of my abilities on how I can dowse to find sought objects, with the physics that came from electrical classes, a college physics class, educational books, and educational TV programming. If a group of open-minded physicists say one of the theories is not this way but is that way, then I stand corrected, and we go by the group of open-minded physicists’ theory.

The author seems to have a very faint understanding of science despite the fact that his book is titled “Separating Science from Superstition”.

Fercik explains his own theory of the concept of “elemental magnetism”. It’s important to clarify what the word “theory” means in the realm of science. People often claim something is “just a theory” or “I have a theory”. That word has a specific meaning in science. A scientific theory is an explanation of the natural world that makes testable and verifiable predictions. Those predictions must be confirmed by experiments using the scientific method. You can’t have a theory without it being able to make predictions that can be verified by other people, otherwise it’s just a guess and doesn’t have anything to do with science.

Fercik goes on to explain that each element in the periodic table has its own unique “elemental magnetism” and that a dowsing rod can “tune in” to that unique characteristic similar to a radio tuning to a radio station. He claims that you can tune in your rod by attaching a “one-tenth troy ounce” piece of silver, for example. Then your rod is tuned for silver. He emphasizes that it must be 99.999 percent pure silver or gold or else it won’t work.

The author claims that a dowsing rod and metal detector work in similar ways and that the dowsing rod is powered by “human neuron electrical signals”. Apparently walking while dowsing builds up a static charge strong enough to move the rods when your target is close.

Fercik claims that metal detectors and dowsing rods both work by “picking up the unique emitted elemental magnetic flux lines of the targeted element or targeted elemental mass.” In reality neither device works that way.

Metal detectors transmit an electromagnetic field from the search coil and any magnetically susceptible metal objects that are close enough and large enough become energized and retransmit their own field. A second coil receives the field transmitted by the metal objects. It’s a similar concept to electromagnetic geophysics such as HLEM or aerial TEM. Modern metal detectors are able to differentiate certain phase responses and that allows them to discriminate between different metals such as gold and iron. When metals have a similar phase response such as tin foil and gold it’s hard to tell the difference.

The author describes the movement of the dowsing rod as the result of closing a circuit and allowing static electricity to flow. According to the book, when in contact with the sought element’s “elemental magnetic flux lines” a circuit is created and the dowsing rod connects the static electricity of the human body’s nervous system with the “elemental flux density” of the sought element.

The author goes on to introduce numerous other terms related to magnetism that he created from his own imagination. His ideas don’t meet the criteria for a scientific theory, they could be easily tested but there is no evidence of that in the book. He also fails to recognize that water is not made of a single element, it’s composed of hydrogen and oxygen.

The author should have consulted someone with a background in physics or chemistry instead of his emphasis on “educational TV programming”. Scientists aren’t hard to find, however, had he done that there wouldn’t be a book to write since it would have been debunked before it even reached the publisher.

Ideomotor Effect

Dowsing rods have been shown to work on the same principle as a Ouiju board. The rods, or the planchette in the case of the Ouija board, are moved by human muscles not ghosts, magic or “elemental magnetic flux lines.” The reason the operator isn’t aware that they are actually moving the object is what’s referred to as the ideomotor effect.

The ideomotor effect was discovered by William Benjamin Carpenter in 1852 and describes the movement of the human body that is not initiated by the conscious mind. Your body moves without requiring conscious decisions all the time. In sports it’s referred to as muscle memory. Driving a car is another example, or playing a musical instrument.

When you are startled or accidentally touch something hot your body is able to move in a way to protect you without conscious input from your brain. Many experiments have shown that under a variety of circumstances, our muscles will behave unconsciously in accordance with an implanted expectation. As this is happening we are not aware that we ourselves are the source of the resulting action.

One of the first people to study this effect was the famous scientist Michael Faraday who also established the basis for the concept of the electromagnetic field in physics among many of his important contributions to the world of science. During the time of Faraday’s ideomotor experiment, in 1853, mysticism was at an all time high and Ouija boards were very popular. He set out to determine what the real force behind the Ouija board was.

Faraday’s experiment was simple. He placed a small stack of cards on top of the Ouija planchette (the piece that you put your hands on). In this experiment, if the force was coming from the participant’s hands the top of the deck of cards would move first. If there was another force the bottom cards would move first. What Faraday and others have shown in every case is that the force was coming from the participant’s hands and not some external entity.

Ouija board dowsing gold

Modern experiments have been done to test dowsing using high-speed cameras. It has been shown that the force on the dowsing rods comes from the person and not from an external force.

It’s interesting that today’s purveyors of the technique insist that testing needs to be done by “open-minded” scientists as if there is some kind of conspiracy against dowsing. There is no conspiracy, in fact there have been a lot of scientific experiments conducted to test the dowsing.

Take a look at some of the studies mentioned below. This is by no means a comprehensive list, there are hundreds of studies on this subject.

Chris French 2007

Psychologist Chris French conducted a double-blind study on dowsing in 2007. The study was filmed as part of a TV show hosted by Richard Dawkins.

Professor French had this to say about the dowsing experts that took part in the study:

I think that they are completely sincere, and that they’re typically very surprised when we run them through a series of trials and actually say, at the end of the day, “Well your performance is no better than we would expect just on the basis of guess work.” And then what typically happens, they’ll make up all kinds of reasons, some might say excuses, as to why they didn’t pass that particular test.

Ongley, P., 1948

New Zealand Diviners

Ongley tested 75 professional water diviners in New Zealand in 1948. The report, linked above, is quite interesting, it discusses some of the history and methods available at the time.

Ongley concluded, “If the seventy-five diviners tested representative of all occupations and from all parts of New Zealand, not one showed the slightest accuracy in any branch of divination. That 90 percent of the diviners are sincere does not lessen the harm that they do.

Vogt, E & Hyman, R, 1959

Water Witching, U. S. A.

Vogt and Hyman argue at some length that anecdotal evidence does not constitute rigorous scientific proof of the effectiveness of dowsing. The authors examined many controlled studies of dowsing for water, and found that none of them showed better than chance results.

Taylor, J. G. & Balanovski, E., 1978

Can electromagnetism account for extra-sensory phenomena?

In this study John Taylor and colleagues conducted a series of experiments designed to detect unusual electromagnetic fields detected by dowsing practitioners. They did not detect any.

Foulkes, R. A, 1971

Dowsing Experiments

Experiments organized by the British Army and Ministry of Defence suggest that results obtained by dowsing are no more reliable than a series of guesses.

McCarney, R et al, 2012

Can homeopaths detect homeopathic medicines by dowsing? A randomized, double-blind, placebo-controlled trial

This study took place in 2012 and studied a different part of the dowsing technique. The study states: “According to the theory of psionic medicine, every living thing and inanimate object is continuously vibrating at a molecular level. This vibration is sensed subconsciously by the dowser, and it is then amplified through the pendulum or other dowsing device.”

Participants were tested on their ability to detect naturopathic medicine vs a placebo in double blind trials. The study showed that the experienced dowsers were not able to identify the correct substance with results better than chance alone.

Whittaker, W, 2013
Grave Dowsing Reconsidered

This study is a review of previous experiments which was put together by the office of the state archaeologist at the University of Iowa. The study concluded:

Simple experiments demonstrate that dowsing wires will cross when the dowser observes something of interest; this is an example of the subconscious ideomotor effect, first described by Carpenter (1852). This does not disprove dowsing, but demonstrates that simpler explanations can account for the phenomena observed by dowsers The premise that dowsing rods cross when exposed to a large magnetic field created by a subsurface anomaly runs contrary to basic scientific understanding of magnetic fields, and does not hold up under simple experiment.

One Million Dollar Paranormal Challenge

The One Million Dollar Paranormal Challenge is an offer by James Randi, a famous magician, to anyone who could demonstrate a supernatural or paranormal ability under agreed-upon scientific testing criteria.

In his book, “Flim-Flam! Psychics, ESP, Unicorns, and Other Delusions”, Randi describes one of the tests that he conducted in 1979 where four dowsers took an attempt at the prize.

Amazing Randi

The prize in 1979 was $10,000 and he accepted four people to be tested for their dowsing ability in Italy. The conditions were that a 10 meter by 10 meter test area would be used. There would be a water supply and a reservoir just outside the test area. There would be three plastic pipes running underground from the source to the reservoir along different concealed paths. Each pipe would pass through the test area by entering at some point on an edge and exiting at some point on an edge. A pipe would not cross itself but it might cross others. The pipes were 3 centimeters in diameter and were buried 50 centimeters below ground.

Valves would select which of the pipes water was running through, and only one would be selected at a time. At least 5 liters per second of water would flow through the selected pipe. The dowser must first check the area to see if there is any natural water or anything else that would interfere with the test, and that would be marked. Additionally, the dowser must demonstrate that the dowsing reaction works on an exposed pipe with the water running. Then one of the three pipes would be selected randomly for each trial. The dowser would place ten to one hundred pegs in the ground along the path he or she traces as the path of the active pipe. Two-thirds of the pegs placed by the dowser must be within 10 centimeters of the center of the pipe being traced for the trial to be a success. Three trials would be done for the test of each dowser and the dowser must pass two of the three trials to pass the test.

A lawyer was present, in possession of Randi’s $10,000 check. If a claimant were successful, the lawyer would give him the check. If none were successful, the check would be returned to Randi.

All of the dowsers agreed with the conditions of the test and stated that they felt able to perform the test that day and that the water flow was sufficient. Before the test they were asked how sure they were that they would succeed. All said either “99 percent” or “100 percent” certain”. They were asked what they would conclude if the water flow was 90 degrees from what they thought it was and all said that it was impossible. After the test they were asked how confident they were that they had passed the test. Three answered “100 percent” and one answered that he had not completed the test.

When all of the tests were over and the location of the pipes was revealed, none of the dowsers had passed the test. Dr. Borga had placed his markers carefully, but the nearest was a full 8 feet from the water pipe. Borga said, “We are lost”, but within two minutes he started blaming his failure on many things such as sunspots and geomagnetic variables. Two of the dowsers thought they had found natural water before the test started, but disagreed with each other about where it was, as well as with the ones who found no natural water.

Cargo Cult Science

Dowsing has never actually passed any real scientific test. That has nothing to do with how “open minded” the scientists doing the study are. Science does not rely on opinion, it’s simply an unbiased way of testing and explaining the natural world. True science does not try to prove a hypothesis, a real scientist should try their best to disprove the hypothesis and only when all attempts to disprove it have failed can we draw the conclusion that the phenomenon is true.

The famous physicist , Richard Feynman, described this perfectly in his 1974 commencement address to the graduating class of Caltech. It’s a great speech that touches on pseudoscience and cargo cults. Check out the video below.

Dowsing is a pseudoscience, at best, and attempts to explain dowsing would definitely fit into Feynman’s description of Cargo Cult Science.

It would be amazing if a prospector could actually pick up two metal rods and walk around until they find a high-grade gold deposit. The idea is very appealing, and that desire is what has kept it around for so many years. If that actually did work, everyone would be able to find gold in large quantities and the practitioners of dowsing would all be multi-billionaires.

Even if you ignore the scientific studies and everything else mentioned in this article it’s pretty obvious that the practitioners of dowsing have failed the fundamental logic test. If they have the magical ability to find gold by holding two rods, shouldn’t they have tons of gold in their possession?

I have had long conversations with numerous expert dowsers. Except for a few that get paid to dowse for water, they all have a day job and dowse as a hobby. Dowsers all swear that the technique works and is effective but they don’t have any gold to show for it. I have yet to meet a dowser that has discovered billions of dollars worth of gold and lives in a mansion.

It is possible that there is some hidden force that we don’t yet understand that can be tapped into using the human body and two metal rods. That’s the idea promoted by dowsing practitioners. They claim there are unexplained “frequencies”, “harmonic molecular resonance”, “elemental magnetism” or other clever-sounding phrases that science hasn’t yet been able to explain.

Carl Sagan famously stated, “Extraordinary claims require extraordinary evidence.” The claims made by dowsers are certainly extraordinary. The extraordinary evidence has yet to present itself.

If you’re waiting for the discovery of a magical force that presents signal lines to buried gold that only a specialized few are able to pick up on with their innate abilities, I wouldn’t hold your breath. It’s far more likely that the phenomenon of dowsing is little more than a self-delusion brought on by unconscious movements in response to implanted expectations, also known as the ideomotor response.

I’d love to hear your thoughts and personal dowsing stories. Feel free to post them in the comments below.

Placer Exploration in the Yukon

Placer Exploration in the Yukon

In the spring 2016 I was hired to help on a large scale placer exploration program in the Yukon. The property is located in a part of the Yukon where very little placer activity has taken place. We had a small team of three guys and a lot of equipment.

HayesValleyYota

The Yukon, like BC and Alaska, was explored and settled by prospectors in the late 1800s.  The Klondike gold rush of 1896-1899 was the largest and most storied gold rush in history.  It is estimated that over 100,000 gold seekers migrated to the Arctic territory from places like San Fransico and Seattle.  The Yukon’s economy is still driven by mining and the local culture is completely saturated with gold rush era influences.  A great example is Yukon Gold, the flagship beer of the Yukon Brewing Company, has part the the famous poem “The Cremation of Sam Mcgee” on the label.

YukonGold

The Robert Service poem is part of Canadian heritage and is part of the school curriculum across the country.  After several trips prospecting in the Yukon it takes on different meaning than a quirky poem that you have to read out loud in grade three.

There are strange things done in the midnight sun
By the men who moil for gold;
The Arctic trails have their secret tales
That would make your blood run cold;
The Northern Lights have seen queer sights,
But the queerest they ever did see
Was that night on the marge of Lake Lebarge
I cremated Sam McGee.

On a Monday night in early April at 9PM I received a phone call. “Your flight leaves Vancouver in the morning for Whitehorse. We’ll fill you in on the way.” Typical for this kind of job. I had been expecting the call for a few weeks but it still caught me a little off guard.

Approximate location of the camp
Approximate location of the camp

On arrival to Whitehorse I had been advised that one of our crew would meet me there. I had never met this guy before but I knew he was an old placer miner. The Whitehorse airport is small and we were the only flight. There were several people waiting for passengers so I had to guess. I noticed a guy wearing rubber boots and looked like a placer miner to me. I introduced myself and luckily he was the right guy.

Aerial shot of the placer claims
Aerial shot of the placer claims

We spent a couple hours rounding up additional gear before catching the charter to the camp. I was crammed in a Cessna 206 with the pilot and a bunch of gear. We had all the 5 gallon pails we could buy at the Whitehorse Home Hardware, drill bits, my gear, a 45 gallon drum of diesel, and a bunch of other stuff.

Soon after leaving Whitehorse we flew over Lake Lebarge which is the location where Sam Magee was famously cremated.

LakeLabarge
Lake Lebarge

The pilot warned me that the runway was a little rough. We took a couple passes and lined up to land. It was rough all right, made of gravel and ice, we bounced so hard that we almost took off again. My two crew members were waiting to greet me at the plane. They were excited to meet me, especially since I brought a 24 pack of Kokanee. The beer didn’t last the night.

DSC01591 DSC01640

The two guys that I was working with had already been there for several weeks. It’s a rustic camp and there was no water available for showers or anything. I thought my team mates smelled pretty bad when I arrived but after a few days we all smelled the same. A few weeks later temperatures were high enough to rig up a pump system and a shower. This is not the first rustic camp that I’ve been to where we have satellite internet and no showers.  These are interesting times to be an explorer.
TheCamp

The camp consists of three canvas tents, a seacan and an outhouse.  The tents have “hippy killer” stoves that burn wood.  They work well most of the time but you have to chop wood every time you want heat.  Wood floors had been constructed which is certainly a luxury over dirt floors.  Our kitchen is in the same tent as the office.  There’s a propane stove/oven and plenty of food.  We used paper plates so we wouldn’t have to wash them, they worked great for starting the stoves when we were done with them.

InsideTent

The main goal of this program was to carry out a sampling over the property.  The drilling and sampling will allow us to find and evaluate economic placer deposits. Our primary tool was a Nodwell mounted drill with a 12″ auger. Some areas were sampled by excavator where the ground was not suitable to drill. Material was collected with the drill and excavator and processed on site with a small wash plant. In addition to gold values we developed an understanding of bedrock depth, characteristics and the distribution of placer gold.

Our Auger Drill
Our Auger Drill

Most of the gear was brought in on the winter trail. The trail is about 100km from the closest dirt road and requires the ground to be frozen and snow covered. Our two Nodwells, Toyota track truck, quads, fuel and everything was brought in over the trail. With a light load it can be travelled by snowmobile in about 4 hours each way. With the heavy equipment it takes 3-4 days. There are impromptu camps along the way but nothing with heat and very little shelter. The guys were prepared of course.

On the trail
On the trail

Nodwells are pretty cool machines.  They were invented in the 1950s to service the oilfields of Northern Alberta and the Arctic.  These beastly machines have super wide tracks to spread their weight on soft terrain.  They have a unique drive system that uses rubber tires on the track.  Operating one is similar to driving a tank.  You pull levers to brake the track on either side.  We had two of them, a big Nodwell for the drill and a smaller one for a support vehicle.  The Nodwells have a lot of character, check out the yellow plywood interior and gun rack.  The small one is named “Picasso”.  The photos will expand when clicked.

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We located and mapped several trenches that were used for ground sluicing dating back to the 1898 Yukon gold rush. The old timers diverted the creek to flow through hand cut trenches. The water was then controlled via a series of gates to strip away overburden. Sort of like hydraulicking. There’s not much left of the old workings today but it gives us an idea of where the pay streaks are.
Old Timer's Trenches
Old Timer’s Trenches

Sampling is key to any placer operation.  Sloppy or inadequate sampling spells the death of many mining operations.  After all you wouldn’t get married without going on a date first.  We collected samples with a rugged 12″ auger drill.  Each sample had a set depth interval and a measured volume.  With accurate measurements we can extrapolate the sample data to evaluate the deposit over large areas.  For example if we sample 500mg (1/2 gram) from 10 pails of material,  that equates to just over 3 grams per cubic yard.  We did have some just like that, and better.

Fresh Drill Samples
Fresh Drill Samples

After collection by the drill our samples were run through a mini wash plant.  We were using a cool machine called “The Prospector” by Goldfield Engineering.  The Prospector uses a water driven pelton wheel to create a vibration.  That’s awesome because all it needs is a 2″ pump to run.  The wheel rotates an eccentric weight similar to the way the a cell phone vibrates but on a larger scale.  Using this machine I processed over 15 cubic yards of samples over 7 weeks.

IMG_5775IMG_5776

The Prospector really eats through material.  The shaker screen breaks it up almost as fast as you can feed it. It struggles when there is a lot of clay though.  After each sample interval is run a cleanup is necessary.  With this machine it’s a quick procedure.  The concentrates from each sample are panned out with a gold pan.  The gold is then dried out and weighed to be used in grade estimates.

DSC01613ProspectorCrop

As the summer solstice approaches the days get longer in the Yukon.  In the summer the sun does not set in the Arctic it is after all the land of the midnight sun.  The lack of darkness takes a little getting used to.  In early May we had a couple of Northern lights shows that were pretty good.  At that time there was about 2 hours of darkness where the Northern lights were visible.  A week later it would no longer be dark enough.

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

We encountered few animals on the trip.  This is described as a “hungry” part of the Yukon.  One bear tried to enter our camp.  It was a very large black bear, the electric fence slowed him down but it took a few bear bangers to scare him off.  A huge mangey wolf casually pranced right in front of us one night.  All the animals are big in the Yukon.  Even the mosquitoes.  They are so big that they often get up and fly away after you swat them.  Unless you are willing to really smack yourself in the face, they are not going to die.

Mosquito

For some samples we had to use the excavator.  The auger drill does not work well in areas where the permafrost has melted.  We tried a few spots and the mixture of water and loose gravel would not stay on the auger flights.  The excavator does not have that problem since it scoops up a bucket full of material, water and all.  We used a huge 4″ pump to drain the holes first then sampled the bedrock and regolith with the hoe.  The samples were of course put into pails and we measured the volume before processing.

pump DSC02030

We had a few other machines to help out as well.  A couple of bulldozers, some quads, a side by side and a ’96 Toyota pickup with tracks instead of wheels.  We took the tracks off once the snow was all gone using the hoe to lift the truck.  Why bother with jacks when you have those Tonka toys kicking around.

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The winter trail conditions rapidly deteriorated as the weather warmed up.  The ground here is like muskeg with lots of water and mud.  Just about everything got stuck at some point, except for the Nodwells.  We had to cross a few creeks, mud and sometimes straight trough the trees.

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DrillTowDozer

The pursuit of gold will make men do strange things.  In our case it involved a ton of work travelling over unforgiving terrain to drill holes down to bedrock.  Our persistence and determination paid off though and we discovered a pay channel that extends over much of the drilled area.  It is going to take some more work to map out the full extent but we already have clear evidence of a great deposit.

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After 50 straight days it was time to go home.  Our ride out was a DHC-3 Turbo-Otter, an impressive aircraft designed by de Havilland, a Canadaian company, in the 1950s.  The Otter took our whole crew and all our gear without any issues.  The turbine engine gives it the STOL capabilities to takeoff and land in a rugged bush airstrip like the one in this camp.  We stopped along the way to drop off one of our guys and pick up some much needed beer before landing in Whitehorse.

I had a wild night in Whitehorse to close off the trip before heading home to BC.  It was a good time in the bush but it is nice to return to the comforts of modern civilization.

Mining the Ocean Floor with Robots

Mining the Ocean Floor with Robots

Mining under Earth’s oceans is just starting to happen.  We have gotten pretty good at mining deposits that are accessible by land but 71% of the Earth’s surface is covered by water.  To date no large scale mining operation has succeed under the ocean which means that it’s all virgin ground.

Amazingly the human race has spent more time and money exploring outer space than we have under our own oceans.  Over 500 people have been to space while only three have ventured to the deepest part of the ocean, the Mariana Trench.  We have better maps of the surface of Mars than the bottom of the ocean, although the ocean maps are pretty cool.

ocean_floor_map

The same geological processes that happen on land also take place under the ocean.  There are volcanoes, mountain chains, faults and earthquakes.  All the same types of mineral deposits occur under the ocean such as epithermal gold, porphyry, and placer.  There are also diamond pipes, massive sulphides and everything else that we mine at the surface.

Deposits

The ocean also has types of deposits that we can’t find on land.  One special mineral deposit is called Polymetallic Nodules.  These are concretions of metallic minerals that occur under the ocean.  The nodules grow sort of like stalactites do in a cave, over time layers of metallic minerals precipitate out of seawater and add to the nodule.  The growth of nodules is one of the slowest known geological processes taking place at a rate of one centimetre over several million years.

noduleBig2nodules_floor

Polymetallic nodules are roughly the size and shape of a potato and contain primarily manganese as well as nickel, copper, cobalt and iron.  They can be found on the sea floor or buried in the sediment.  Nodules can technically occur anywhere in the ocean but seem to be in greatest abundance on the abyssal planes around 5000m deep.  Nodule mining would be similar to placer gold mining except under water.

Anouther resource that is unique to the ocean floor is Ferromanganese Crusts.  These are similar to nodules but occur as a coating on other rocks.  These crusts can be found all over the ocean with thicknesses ranging from 1mm to 26cm.  Ferromanganese crusts typically occur in the vicinity of underwater volcanoes called seamounts or near hydrothermal vents.  Crusts with mineral grades that are of economic interest are commonly found at depths between 800m and 2500m.

Crust
Ferromanganese Crust

Ferromanganese crusts are composed primarily of iron and manganese, hence the name.  Typical concentrations are about 18% iron and 21% manganese.  Cobalt, Nickel and Copper occur in significant quantities as well.  Rare earth metals such as Tellurium and Yttrium can be found in metallic crusts at much higher concentrations than can be found on the surface.  Tellurium is used in solar panels and is quite valuable.

Sea-floor massive sulphides (SMS) are a younger version of volcanic massive sulphides (VMS).  The two deposits are similar except that VMS are typically ancient and SMS are currently forming.  SMS deposits occur where superheated hydrothermal fluids are expelled into the ocean.  They typically form around black smokers near continental rift zones.  SMS are know to hold economic concentrations of Gold, Copper, Silver, Lead, Nickel and Zinc.

BlackSmokerHiRes
BlackSmoker

Black smokers create SMS deposits by expelling superheated sea water that is rich in metallic elements.  Cold sea water is forced through the sea floor by the pressure created from the weight of the water column above it.  The water is then heated to temperatures in excess of 600°C when it is brought close to the magma that lies below.  The heated water becomes acitic and carries with it a high concentration of metals pulled from the surrounding rocks.  Once the hot, metal rich, water comes into contact with cold sea water the metals crystallize and deposit on and around the black smoker.

Mining

Large scale ocean floor mining has not taken off yet.  Attempts have been made since the 1960s and 70s  but failed due to technological and financial challenges.  Small scale shallow ocean mining has been a lot more succesful in recent years.  A great example is the popular TV show Bering Sea Gold.  The miners in Nome Alaska are using modified suction dredges to comb the sea floor in shallow waters.

Currently proposed sea floor mining ideas are essentially super high-tech placer mining.  They involve ways to dig through the surface layers of the ocean floor, bring the material to the surface and ship it to a processing facility.  Its a lot like dredging but on a massive scale.  As mentioned above, normal hard rock deposits also occur under the ocean but no plans have been proposed to build open pit mines under the ocean.  That would involve all the challenges of building a mine on land with the added complexity of operating under the ocean.

Why is ocean floor mining possible now when it wasn’t 20 years ago?  The answer comes down to one word, robots.  The world of under water mining is the domain of autonomous drones and human controlled ROVs.  Robot submarines are nothing new, they have been around since the 70s and have been used to explore depths of the ocean that are very difficult for humans to get to.  UUVs or unmanned underwater vehicles are a little bit newer, they are basically an autonomous version of ROVs.  Ocean mining robots have just been invented and share a lot of the technology used in these devices and they look like something straight out of science fiction.

cutter
The Cutter

The first deep sea mining project is currently being developed off the coast of Papua New Guinea.  The project is called Solwara 1 and is being developed by a Vancouver BC mining company called Nautilus Minerals.  Solwara 1 is a copper/gold SMS deposit with estimated copper grades of 7% and gold grades in excess of 20g/t and an average gold grade of 6g/t.  The property sits at about 1600m depth.

Nautilus has developed a suite of underwater mining robots and a complete system to mine the precious metal and bring it to shore.  There will be the bulk cutter pictured above, an auxiliary and a collection machine.  Please take a moment and marvel at these amazing achievements of engineering.

Transporter Bridge TeessideTransporter Bridge Teesside
 After the robots dig up and collect the ore a custom designed Riser and Lift System (RLS) will bring the material to a giant ship that acts as the mine control center dubbed the Production Support Vessel (PSV).  The RLS is basically the world’s most powerful suction dredge.  It’s pretty complex, this is the description on the Nautilus Minerals website:

The Riser and Lifting System (RALS) is designed to lift the mineralised material to the Production Support Vessel (PSV) using a Subsea Slurry Lift Pump (SSLP) and a vertical riser system. The seawater/rock is delivered into the SSLP at the base of the riser, where it is pumped to the surface via a gravity tensioned riser suspended from the PSV.

Once aboard the Production Support Vessel the mined slurry will be dewatered and stored until anouther ship comes to take the material on shore for processing.  The removed sea water is pumped back down the RALS which adds hydraulic power to the system.  Pretty cool stuff!  Check out the video below for an visual explanation of how it will all work.

Exploration

Ocean floor prospecting is not a good place to be gold panning or hiking around with a rock hammer.  It is also difficult to take usable photos due to poor light and lots of debris in the water.  So how do you explore for minerals in the ocean?  Geophysics and robots.

Geophysical exploration is not unique to the ocean.  The same techniques are used routinely on land to find every type of mineral deposit.  Ocean geophysics is also not new.  The main workhorse of mining exploration is magnetometry.  Which means mapping changes in earth’s magnetic field using a specialized sensor.  The technique was actually developed to detect enemy submarines during World War II.  Since then magnetometers and the science behind them have evolved into accurate tools to measure geology.

I’m using a proton precession magnetometer in the photo below.  There is some sample magnetometer data on the left.  Mag maps look similar to a thermal image except the colour scale represents magnetic field changes (measured in nanoTesla) instead of temperature.

Walk Mag in ActionSampleMag

Magnetometers are excellent tools for ocean mining exploration.  They are not affected by the water and are excellent at detecting metallic anomalies.  There are now underwater drones that can collect ocean magnetometer surveys without the need for human intervention.

Autonomous Magnetometer Drone
Autonomous Magnetometer Drone

Other geophysical techniques have been used in ocean mineral exploration.  Electomagnetics (EM) techniques are also great tools for exploration under water.  EM works in a similar way to magnetometry except that they emit their own source.  Conventional metal detectors are actually a small version of an EM system.  While mag passively measures Earth’s magnetic field EM measures the difference between a source and received pulse.  EM also works great for discovering metallic anomalies and is being incorporated into autonomous drones as well.

There are other types of ocean geophysics such as seismic refraction which uses a giant air gun to send a sound wave deep into the crust and measures the response on floating hydrophones.  Sonar and other forms of bathymetry can provide detailed maps of the ocean floor.  Bathymetry techniques can create imagery similar to LiDAR that is used on land.

Sample Bathymetry
Sample Bathymetry

Ocean mining is just in its infancy and some really cool technology is being used.  Advancements in the robotics have allowed mining and exploration to be completed without a person having into enter the water.  As technology advances further we will be able to explore vast areas of the ocean floor and discover immense mineral reserves that are presently unknown.  It is estimated that we have only explored about 5% of the ocean floor, who knows what we’ll find down there?

7 Common Mistakes Made by New Placer Miners

7 Common Mistakes Made by New Placer Miners

Placer mining is an exciting activity.  It brings us out into the wilderness often to the road less traveled.  There is a certain charm associated with the hunt for gold.  In some ways it feels like an exclusive club where the only entry requirements are the knowledge, skills and the will to take on the challenge of finding precious metal on the earth’s surface.  For those starting out there is a lot to learn and all too often a novice miner’s decisions are influenced by greed or the infamous gold fever.  Here’s a list of some of the most common mistakes made by new gold miners.

  1. Buying too much equipment too early

    LotsOfGear
    Photo Source: www.tambang.id

    Placer miners are total gear nuts, myself included.  To run even a small operation you need a fair amount of gear.  Pans, sluices, digging tools, camping equipment, 4×4 truck, etc.  And there is plenty of gear on the market to spend your money on.

    However more equipment will not necessarily make you more money.  Often its quite the opposite.  In our fast paced consumer focused economy it is tempting to look for a quick fix.  There is no substitute for hard work though. You need to put in the time and effort to find that gold.  I have met several people who have purchased a brand new floating dredge with nowhere to use it.  Fortunately their equipment quickly finds its way onto craigslist at a discounted price.

    Prospecting starts with a gold pan, other tools that help are classifiers, snuffer bottles, and an accurate scale.  Once you have proven gold in an area you can look at moving on to something that can move more material.  The next progression would be a highbanker or a small diameter dredge (if they’re legal in your area).  If you have found enough gold and can’t move material fast enough the next steps are moving to a larger wash plant and possibly heavy equipment.  At each step along the way you need to assess the quantity of gold on your claim and the costs of getting it out.

  2. Buying the first claim that’s available

    ClaimPostIts pretty exciting to have the rights to your first claim.  You start dreaming of all the riches that are now yours for the taking.  Its tempting to snap up the first claim that is available.  Especially in areas with online staking, its a lot like buying concert tickets.  Unlike concert tickets though gold claims are usually available for a reason.  Perhaps the claim has poor access, little to no gold, or has already been mined to death.

    Do some research before you pull the trigger.  Read up on the history of the area to make sure it hasn’t been thoroughly mined already.  Make sure it has good access roads or trails.  Find info on previous production in the area and if possible sample the claim before you buy it.  Check some maps to make sure the claim is not on a park, reserve or private land.

  3. Poor or No Sampling

    SamplesApril

    Effective sampling is absolutely essential to run a profitable placer mining operation. You wouldn’t buy a car without taking it for a test drive.  It is tempting to show up at a claim and start running a highbanker on the first gravel that you see.  Even some larger operations forgo proper sampling in the rush to get mining and lose a lot of money because of it.

    Sampling is not glamorous and you won’t get a lot of nuggets to show your friends but you need to know how much an area will pay before you spend time and money to produce it.Once you have thoroughly sampled an area and have calculated the pay per yard you will know how much you can spend to produce the gold.  For example if an area pays $100 to the cubic yard and your cost is $40/yd to produce it you will certainly make a profit.  Your proven reserve is sort of like a bank account.  You don’t want to spend more money on equipment than your reserves will justify.

  4. Not digging deep enough

    IMG_2420 Almost every novice prospector will sample surface gravels and expect to see flakes of gold.  Placer prospecting and mining hinges on the fact that gold is very dense.  Being heavy, gold will settle deep as it can in a gravel bed.  When digging a test hole you basically want to dig as deep as you can.  You want to reach compacted gravel before you start sampling.  In most cases your best gold will be on the bedrock.  In some areas there are clay layers or river armour layers that will trap the gold.  It will always travel down until something prevents it from sinking any further.

    There are areas where flood gold can be found near the surface.  It is important to know the history of your area.  Even if there is surface flood gold though the real paystreak will always be deeper down.

  5. Lack of knowledge of local mining regulations

    regs Just like other laws it is your responsibility to know the mining regulations for your area.  I have heard too many stories of guys panning or running river sluices in areas that they didn’t even know were claimed.  That is called claim jumping and is illegal.  In the gold rush days it was perfectly legal and acceptable to shoot a claim jumper.  Today claim jumpers can face a criminal record and imprisonment. Check out our post on claimjumping for more info.

    The rules are not the same everywhere.  A suction dredge might be perfectly acceptable in one area and completely outlawed in another.  Dredges and highbankers area also regulated by water intake hose diameter and type of creek that you are working on.  Other regulations to look out for are environmental rules for drawing water and working in riparian zones.

    Laws regarding exploration on private land, provincial parks or first nations land must also be obeyed.  You have certain rights by holding a claim but that does not guarantee your right to dig in every situation.

  6. Unrealistic expectations

    Nuggets These days with the recent flood of gold mining TV shows it seems so easy.  They give the impression that all you have to do is show up with an excavator and a wash plant and you’ll start pulling out nuggets.  Often these shows have some arbitrary budget that the miner needs to reach by the end of the season.  Just seeing numbers like $500,000 per season will get anyone excited.  You may be thinking if they can get that I can at least get $1000 on a random claim.  Spending an hour per night watching guys pour jars full of gold flakes on shows like Yukon Gold or Gold Rush Alaska will fuel unrealistic expectations.

    The fact is gold is valuable because it is incredibly rare.  The value is largely due to the sweat equity of prospectors and miners who have spent lifetimes searching for the yellow metal.  It will be a long road to get your first jar full of gold or even a vial for that matter.  Prospecting for gold has an incredibly poor success rate.  You will put in hard work, digging, hiking and panning for long hours and won’t see more than a color.  Some days you won’t even see that.  Gold is defiantly out there but don’t expect to see any in your first pan.

  7. Improper technique with equipment

    Indian River Yukon
    Most placer mining and prospecting equipment requires skill and knowledge to operate effectively.  That is part of the appeal to prospecting, its a skill just like any other and takes time to develop.  There are a lot of people out there who are not using their gold pans properly and washing gold right out of the pan.  Likewise with highbankers, its a common mistake to mine all day with the wrong angle on your sluice.  There is a lot of info out there on proper techniques don’t just buy equipment and try to figure it out on your own.

    The best thing to do is go out with someone who is experienced with the equipment that you want to use.  You can watch Youtube videos all day but nothing beats hands on experience.  Most placer miners will welcome an extra hand to help work the claim, in the process you will learn everything you need to know.

    If you’re looking for some experienced miners to hang out with, check out the WCP Mining Club.

Gear Review: Pyramid Pro Pan

Gear Review: Pyramid Pro Pan

Placer mining and exploration breeds innovation like no other activity.  Virtually every prospector that you talk to has their own idea of what the best tool, product or technique is.  If you ask three different miners what the best sluice is you’ll get three different answers.  Much of the innovation comes from the trial and error learning process of placer mining.  What works at one claim might not work at the next.  You just have to experiment until everything works the way you want it to.

PyramidPro

The history of placer mining has a long list of innovations and miners benefited with increased yields at each step along the way.  The gold pan was one of the first inventions, then followed the rocker box, sluice, variations of the sluice such as the long tom, hydraulicking water jets, dragline dredges and so on.  The miners in the Klondike gold rush learned to melt the permafrost using fires to reach the bedrock below.  Now they use modern excavators and bulldozers but it had to start somewhere.

Old Time Placer Tools
Old Time Placer Tools

Every inventor claims that their product is the best.  It can be hard to distinguish the good from the not so good.  In the case of the Pyramid Pro pan developed by Dennis Katz at Fossickers.com it is a game changer.  I am not affiliated in any way with the manufacturer of this pan I just really appreciate the technology.  Fossicker is an unusual word, according to their website it is the Australian word for gold prospector.

There are other pyramid shaped pans on the market but this one has some very unique features.  First off it has insane riffles!  These riffles do two things.  They break up clay or hardpack along with the violent action of the pyramid panning motion.  And they prevent any dense material (ie.gold) from escaping.  The violent action must be emphasized.  In conventional gold panning you want to avoid too much force and splashing because you will force your gold right out of your pan but that is the essence of the Pyramid Pro.  The action is hard to describe and best seen in person.  Check out the developer’s own instruction video below to see how it works.

It is a little funny how the Fossicker keeps saying to “stratisfy” the material.  What he really means is stratify, maybe its an Australian thing too.  You hold the pan with those big handles almost like you’re holding a gas powered ice auger.  It is a bit of an arm workout when you are going through a lot of material but the Pyramid Pro is designed to do exactly that.  The experience is very unique and has little to do with conventional gold panning.  The Fossicker calls the neck of the pan a pre-mix chamber.  Once you get the technique down nothing will escape that chamber.

GranitePPan

The most important benefit for prospectors is that this pan is a lightweight unit that can concentrate a lot of material.  It can essentially replace a small sluice or highbanker for a similar amount of material.  Where it pays off the most is in places where you need to hike in to access a claim.  You are not going to hike with a trash pump, sluice and hose for any considerable distance.  With the Pyramid Pro there is no need to.  I’m not saying its going to replace a highbanker or dredge when it comes to production.  Technically it could but you would need forearms like Popeye.

Where this pan really shines is in volumetric sampling.  That means taking a sample of a set volume and using the gold values to estimate the pay over a larger area.  For example you can take a sample of 50 liters of raw gravel.  Concentrate it with the pyramid pan and then separate and dry your gold.  You can then weigh that gold and extrapolate that number to a cubic meter or yard.  As an example if you had 0.025 grams of gold recovered from your 50L sample that would equal 25g per cubic meter or almost an ounce.   With careful sampling you can be confident that the area is worth the time and money to mine it.

SamplesApril

The pressure plug at the bottom makes taking samples super easy.  Once you have concentrated your sample down, you just pull the plug and dump it into a container.  If you were doing the same thing with a highbanker you would have to do a full clean up for each location.  With this tool you can rapidly sample a large area in no time flat.  The plug can be easily replaced if you damage or lose it.  The plug is just a 1.5″ plumbing plug which is available at any hardware store.

The plastic is surprisingly tough.  I had my pyramid pan on the back of my pack on a particularly perilous prospecting mission.  I wiped out on a jagged rock outcrop and landed with my full weight on the pan.  I thought it was going to be toast but was relieved to see that no damage at all had occurred.  Likewise with my other plastic pans.  I don’t know what kind of plastic they use but it is unbelievably durable.  The Fossickers website claims that it has a lifetime guarantee just in case you did manage to break it.

The Pyramid Pro pan is the center of my sampling technique.  The fact that it is ultra-portable and can concentrate a lot of material makes it an indispensable tool for the modern prospector.  They are not cheap though, I paid $120 for mine and its worth every penny.

You can pick up a Pyramid Pro pan at:

SMI Electronics in Vancouver, BC
or
Motherlode Prospecting in Kelowna. BC