Fraser River Unexpected Rock Climbing

PlacerGold Trip Reports May 21, 2015baofeng, gold, gold mining, gold mining equipment, gold pan, gold panning, Lillooet, placer claim, radio, rock climbing 3 Comments

In April I went to check out two claims in the area North of Lillooet, BC. These two claims are close to the one that I wrote about in my Southern Cariboo Prospecting Trip. On the way up the Fraser Canyon I stopped at the old Alexandra bridge to get a peep at a claim that I have on the other side of the river. The old bridge is part of the original Cariboo wagon road that serviced the gold rushes of the Fraser and Cariboo. The Alexandra bridge that stands today was built in the exact same spot of the original bridge from in 1861. The current bridge was completed in 1926. There’s a lot of history here.

In the second photo you can see the latest bridge in the distance that replaced the old suspension bridge in the 1960s. The old bridge has an open grate for a bridge deck. I’m not afraid of heights but it is a little hard to trust a bridge that has been decommissioned. There has to be a reason right?

Once again I travelled up the West Pavillion forest service road to do some gold panning. This time though the road frequency had been changed, and the new one wasn’t posted yet.

There were some phone numbers and a website posted but this area is outside of cell range so that is not really helpful. I had a my trusty Baofeng but it wasn’t any good without the proper channel. Here’s a link to the new posted channels for the area, FYI. According to that site the new channel is 150.11 MHz. Fortunately it was a quiet day on the road and I didn’t see anybody.

I got to the first claim later that day. I found a nice camp site near the dirt road and eagerly began hiking down to the river to take my first samples. It looked pretty steep on the topo maps and with my prior experience in the area I was expecting it to be. The maps were accurate and it was at least as ugly as I had imagined. Loose gravel and significant slope on the way in. I was hoping to find a more civilized route up once I got down to the river.

I managed to get a couple samples before the light started to fade. The samples that I take consist of two full pails each, and partially processed on site. I use the pyramid pan to concentrate that down to about 1L and store the samples in a waterproof zip lock bag for the hike out. It takes at least an hour to excavate each test hole in this area due to the abundance of large rocks making up the beach.

My hope of finding a “civilized” route was not fulfilled, I marked the climbing route in the above photo. I was faced with either hiking up the super steep talus slope or rock climbing up some exposed rock. I chose the rock climbing. I must mention that I am experienced with rock climbing and don’t recommend this course of action if you aren’t comfortable. Its not exactly safe, especially with a backpack loaded with a pick axe, shovel, 5 gallon pail, samples, gold pans and all the other prospecting gear. Not to mention no rope.

I made it up OK, with a little bit of a gut check at the top, then hiked the rest of the steep slope up to the camp for some well deserved beer and food. Little did I know that was just the beginning of the unexpected climbing on this trip. On the previous trip to this area we thought that climbing ropes and gear might be needed for these claims but it was impossible to tell until you come over the edge towards the river.

The second claim was just down river from a small canyon. This is a good thing for trapping gold but it does not make for easy access. It all looked good on the way down but it dropped off steeply as I descended towards the river. Pretty soon I found my self perched on top of what was a near vertical drop. I spotted a line down but I couldn’t see the whole path. At this point I was committed. The further I descended the worse it got and next thing I knew I was reverse rock climbing down to the beach.

Once again I hoped that I would find a better route up. This time around I knew it wasn’t going to be easy. I had a whole day of sampling to do so I’d worry about climbing out when the time comes. I managed to get three good samples from the beach and inevitably the time came to climb out. I knew the way in was very dangerous and didn’t know if I even could climb back up. The photos below show the route to the beach.

I spotted a route to rock climb out but it was nasty too. It looked like solid rock with good holds so I went for it. It turned out not to be solid and almost every hold I grabbed broke loose and slid down the slope. I got to a point about 3/4 the way up the rock climb section where I was certain that I was screwed. No way up and no way down. Not a good feeling. After several minutes of gathering my courage I decided I had no choice and went for it. Once I was on top and able to walk on my feet I was relieved and more than happy to hike up the rest of the steep slope to my camp. I didn’t get a great picture of the route up from the beach. The photo below shows the approximate route.

I’ve gotten myself into these sort of situations more times than I’d like to admit. Honestly though the unexpected situations are one of the most exciting parts of prospecting. At the time you are terrified and wonder how you ended up in this situation but afterwards those are some of your best memories. Without a sense of adventure who would go out to these places looking for gold? As luck would have it, these claims actually had some decent gold. The trouble is how am I going to get in there next time?

Where Does Placer Gold Come From? – Part 2 Deposits

PlacerGold Science May 14, 2015carlin trend, epithermal, gold, gold mining, greenstone, lode gold, mother lode, placer, porphyry, quartz vein 3 Comments

In part 1 of “Where Does Placer Gold Come From?” we discussed the origins of gold and how it appeared on earth. Now we’ll discuss how it moves into mineable deposits.

Gold is spread relatively evenly throughout the crust of the earth at approximate concentrations of 1 part per billion. To put that into contrast, low grade mineable gold deposits need to be concentrated to at least 1 part per million which is about 1000 times more concentrated than the background. High grade gold deposits are in the order of 20-100 ppm. Gold concentrations are usually expressed in grams per ton, which is interchangeable to ppm.

So if gold is evenly spread through the crust how does it become concentrated? There are several natural processes that allow this to happen and they are all driven by the same force, plate tectonics. Plate tectonics is the force that moves continents, creates mountains and most volcanoes, and of course earthquakes. The image below shows the current tectonic plates and their names.

The plates are constantly moving, crashing into each other and subducting, they are pushed by convection currents in the mantle. In the distant past there have been several supercontinents where all the continents had come together to from one. Past supercontinents have names like Rodinia, Godwana and Pangea, it is predicted that a new supercontinent will occur in the next 250 million years.

At the boundaries of these plates is where the excitement happens. It is at these areas such as the West coast of North America where volcanic processes squeeze gold into veins. There are two main ways that this happens. Orogenesis (mountain building) takes place as the force of two plates hitting each other forms mountains as the edges of the plate buckle and slide. In the mountain forming process rock is squeezed to the point of breaking and creates fissures and faults that extend deep into the crust. These cracks allow heated and pressurized water to come up the cracks.

The other way is driven by volcanoes forming from the subducted plate. When the edge of the plate is far enough below the surface it re-melts and the newly molten rock builds up pressure. This pressurized molten rock is what forms the volcanic chains inland from the subduction zone. As volcanoes form they crack and fissure the surrounding rock and contribute to the same epithermal process.

Imagine the rock as a sponge and when it is squeezed the water is expelled through the cracks. It is actually the same way that hotsprings work but with more squeezing. This kind of gold mineralization often takes place near volcanic or geothermal activity such as hot springs or geysers. When the mineralized water cools it leaves behind the minerals in solid form which we then call a vein. Typically we are looking for quartz veins. Vein deposits are often called lode deposits in artisanal miner vocabulary. Placer miners will often refer to the “mother lode” that is the quartz vein or veins that broke down into rich placers.

There are other hard rock gold deposits other than epithermal lodes. There are Greenstone, volcanic massive sulphides, porphyry and Calrin trend deposits. All of these depend on volcanism as well and occur in similar ways as described above. Areas high in volcanoes and seismic activity are good places to look for gold. The Pacific ring of fire is an area surrounding the boundary of the Pacific tectonic plate. This area contains 3/4 of the worlds volcanoes and is responsible for 90% of the world’s seismic activity. In the gold rushes of the 1800’s prospectors envisioned a world wide gold belt. It wasn’t until the 1950’s that plate tectonics became an accepted scientific theory and decades later we mapped out that gold belt.Of course not all gold is found in the ring of fire. The largest known gold deposit on earth is in Witwatersrand, South Africa. It is estimated that 50% of the gold mined on earth has come from this mine. Witwatersrand is actually a huge placer deposit from 3 billion years ago. In my next post we’ll finally get to the formation of placer gold deposits. Stay tuned.

Check out Part 3 on how gold placers form:

Where Does Placer Gold Come From? – Part 3 Placer

Where does placer gold come from?

PlacerGold Science May 9, 2015gold, gold mining equipment, gold pan, lode gold, placer, solar system, supernova 0 Comment

If you are trying to find gold it helps to know where it came from.

To start with there is only one kind of gold. Placer gold and lode gold both come from the same place and are made of the same stuff. Gold is not actually formed on earth it was formed millions of years ago in distant stars. In large stars, much larger than our sun elements are combined together in their cores through the process of nuclear fusion. Our sun like all stars runs on fusion too but it does not have enough mass to produce atoms larger than carbon or oxygen. Larger stars can generate the gravitational force and heat in their cores necessary to produce elements as heavy as iron. To create things like gold even more energy is required and that takes place in a supernova.

When a large star runs out of light matter the fusion reaction is no longer sustainable and the star begins to collapse on itself very rapidly. The supernova collapse takes place in a matter of seconds. While the star is collapsing it produces heat very rapidly and explodes in what is essentially a humongous nuclear bomb. Supernova events are so bright and powerful that they are brighter than then entire galaxy that hosts the star. This nuclear explosion allows for higher energy fusion reactions that can produce heavy elements like gold. The explosion also scatters the newly created material over great distances.

So how did the star dust make it into the mountains and rivers on earth? When our solar system began approximately 4.6 billion years ago it was a cloud of dust and gas called a nebula. This nebula was composed of the remains from older stars that had spread their guts around the universe in supernova explosions. The molecules of the nebula naturally pulled on each other by the force of gravity growing more and more dense. As the nebula was collapsing in on itself it also started to spin faster and faster. The condensing and spinning action formed the nebula into a disk, much like you spin dough into a pizza. In the center where the force of gravity is the strongest a new star was created, our sun. The swirling mass around the sun clumped together into the planets, moons, asteroid and comets that we see today.

The early solar system was different that it is today. The big planets did not form all at once, it was a gradual process. Small plantoids formed first and crashed and coalesced into each other to form larger planets. In theory the distribution of gold was basically even in all the rocky material that made up the early solar system. In the early earth, while it was still completely molten the heavy material (such as iron and precious metals like gold) all sunk to the center of the planet to form the core. The process is similar to the way that dense material sinks to the bottom of your gold pan. If you could mine the core you would be very rich but it would be very difficult with current gold mining equipment. Current scientific theories estimate that there is enough gold in the core to cover the surface of the earth with a 4 meter thick layer of pure gold.

We can only reach gold that is trapped in the crust of the earth. The precious metals in the crust were put there by meteor bombardments that took place after the crust had formed. As these meteorites crashed into the surface of the earth they disintegrated and mixed their material into the upper mantle. The meteorite guts had the effect of enriching the amount of precious metals in the crust.

So we know where gold came from and how it was formed. Stay tuned for a future post to learn how the gold formed into deposits in the mountains and streams that we mine.

Check out Part 2 & 3 here:

	How to Get Started in Gold Mining
	Search for Slumach’s Lost Gold Mine
	Types of Placer Wash Plants
	Top Ten Gold Rushes of BC
	How to Lose Your Shirt in Placer Mining