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siggy wrote:

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I've wondered if flour gold and colours collect in voids and get worked by weight of moving rocks, etc until they become a small flat nugget.
Sort of hammer welded..??

Good point, Tony. If that really was a way for mother nature to make small gold pieces into larger pieces, like nuggets, then we should be finding pieces of gold in the process of being hammered together,...., like a dime being hammered onto a quarter. I haven't seen that as far as I can remember. I have seen nuggets in the process of being squished into 2 pieces, where a rock edge smashed down on the nugget. like squeezing a piece of toffee in the middle. I am sure many nuggets could very well have been hammered together. Hard to tell after further wear. I have seen places with 2 types of gold in the same gravels. Different colours, textures and assays. Obviously from different veins from a wide area. I never did see a 2-tone nugget where different golds got hammered together.

My first sniping experience was when I was a kid in St. John's Newfoundland. I was sniping the cracks in the river bedrock, not for gold, but for coins. Some coins were hundreds of years old and it seems every one of them was jammed vertically into the slaty bedrock full of vertical crevices. It seems coins and flat nuggets will flip and roll when they are not laying flat on the bedrock, getting hammered flatter and flatter.

Some say that the nuggets found in the White Channel gravels in Dawson City, Yukon, were formed by gold rich fluids that percolated out of the earth's crust into the thick layer of snow white quartz pebbles that originally were quite barren of gold. Agglomeration. The nuggets grew, in place. This theory makes sense, because the gold was found several feet above bedrock. The white mountain of quartz pebbles, boulders and gravel had no gold contained within the quartz pieces. And there are gold solutions still rising from the bedrock in Dawson. Give another few eons and maybe the Klondike nuggets will grow back!

Bornwithatooth wrote:

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Soo... what you are suggesting is that the gold rich "fluid" seeps up through the cracks and solidifies as what we see when we bust apart the chunks. The flat gold in my bedrock may have grown "in place" and not introduced by other means. I could believe that. Now I will be looking for much wider cracks.

Hey, Born, I think any bedrock crack that had river water flowing over it at one time or another is where you want to look for gold. Explaining how it got there is not nearly as important as putting the gold in your jar or poke. I'd say almost 100% of the time gold gets into bedrock cracks by vibration and gravity. Vibration from the flowing water. Gravity meaning the high specific gravity of gold that makes gold 4 or 5 times more powerful than lighter minerals, to force its way to the bottom of any crack. Once gold is at the botom of a crack there it will be the last mineral to ever be flushed out. So, with the flowing water action, a constant sorting action is taking place in a crevice, the gold concentration getting richer and richer. The river also provides the perfect sized nugget to fit in any crack,...,the nugget that barely fits into a crevice is the one that will be least likely to get flushed out again. I always think of a river bottom being a flow of gravel and water, not just water. Imagine how many millions(?) of cubic yards of gravel will flow, over the centuries, across a crevice in the bottom of a river. Every gold particle in the flow will make an attempt to drop into the crevice.

The most interesting crevice I ever saw was 40 feet under water on a smooth, featureless bedrock floor of the American River, in California. We had removed about 25 feet of gravel and boulders to expose the floor. Used winches and 8-inch suction nozzle. Anyway, there was one "crevice" that we called the letter slot/letter box. It was the same size as the mail slot in your front door. The slot was basically full of gold. We had a 3 foot long blaster pipe which we forced into the crevice. The nuggets would rocket out of the hole and rain down on the operator's shoulders and dive hood and onto the floor.The suction nozzle was there to suck up nothing but gold. There was very little gravel in this mail slot. It showed how the river eventually flushed away any gravel from the crevice and left only gold. We left that crevice at 3 feet depth, being the length of our blaster pipe.
At 3 feet we assumed that the water pressure was not strong enough to push any more gold up from the bottom. The only thing left to do was break open the solid crevice by hammering and mining. We left that project for another day. Never went back. Who knows how much deeper she went. We took over 6 ounces of gold from this crevice.

As for nuggets growing in place, I only mentioned the Dawson White Channel gravels as an example and a possibility. Wherever nuggets come from, they always like to find a cozy crevice to duck into, out of the raging rivers. Much like the riffles of your sluice box.

Any water-worn bedrock, is a place to snipe. Even if the bedock is high and on the side of a cliff. The surrounding bedrock may have worn away over much time, leaving a gold-bearing crevice high and dry.