I had previously asked why the Native Americans, Spanish and Mexicans hadn’t “discovered” gold in California prior to 1848, and I got some pretty good answers, but now I want to ask a different question. <Mods feel free to move this over to IMHO if it’s appropriate.>
During the height of the gold rush there were countless people combing the hills, valleys and streams of California looking for gold deposits. As everyone knows, a lot of gold was found and taken out. Later on, when the easy pickings were gone, there were miners that blasted tunnels while others used water cannons to scour the cliffs for deposits. After some point in time, all the major claims had been “worked”, and therefore few people were getting rich, so miners started to look for other places to plunder.
My question is, how likely is it that there are still a few “significant” undiscovered deposits of gold somewhere in California? Can credible geologists say with any kind of certainty that based on sound geological principlals that the major veins have already been discovered so it’s not worth looking for it?
From the California Geological SurveyIn the years 2000 through 2001 California had 16 significant active gold mines in operation. About half of them were located in the historic Mother Lode Belt. Some areas … may not be currently operational, but the resources may still be present.
It’s important to distinguish between placer gold and the stuff bound in rocks. The former is basically gold that has been “mined” by centuries of water flow. It tends to be deposited along streams, sometimes in significant quantities. It’s rather easy to get hold of - you simply wash away the dirt and gravel, and there’s your gold. It’s also relatively easy to know where to look for it - anywhere water is (or once was) flowing out of hills and mountains. Because it’s easy and relatively cheap to go after this alluvial gold, it tends to be done quickly and rather thoroughly.
Gold that’s bound in rock is usually much less concentrated and much more expensive to mine. You have to move large quantities of rock bearing perhaps an ounce of gold per several tons. The ore is pulverized and the gold is concentrated through some chemical process (e.g. cyanide leaching). The capital cost of setting up a serious mining operation could easily be tens of millions, so there’d better be some serious quantities of ore to process.
So the answer to the OP is that the hordes of folks that showed up for the big gold rush probably covered the ground well enough that the chance of now finding significant quantites of placer gold is quite low. By contrast, it’s nearly certain there’s plenty of gold still in the mountains. Whether this exists in sufficient concentration to be commercially viable is hard to say.
Yes it is possible but the chances of making a living at it are slim.
Gold mining these days requires a large up-front investment and sophisticated recovery methods. A mine not far from here, at Randsburg, CA, was working a lode with an estimated concentration overall of .02 oz/ton of ore. Gold was selling at about $300/oz during its peak production so they had to make money moving rock at $6/ton, and they did.
I would expect that someone could go down to their tailings pile right now and find a little gold here and there.
I was raised in Colorado, which had it’s own gold rush. Ditto what was said about the placer gold. On the mines, at least in the Colorado Rockies, they tended to stop and start operations based on the market price of gold…might as well leave the gold in the ground if the price is too low to profit. So there are a good number of mines that are currently out of operation, not because they are played out, but because the ore is too low grade to be profitable at the current market price. I’ve encountered a couple of these that have “security guards” on site to run off trespassers. Quotes, because the ones I’ve met tend more to fit the stereotype of “deranged old prospector” than “guy in black clothing driving a golf cart”. Trespassing is a problem both from the standpoint of vandalism, but also due to liability.
It can be a fun and occassionaly rewarding hobby. You just need some lessons / pointers and either a pan or better a sluicebox. You are out in the wonderful CA wilderness, getting fresh air and exercise. Any gold is a side benefit. You are certain to find enough to show dudes, and dudes still make an occassional lucky find. I had friends in Modesto that did this most every weekend, and what they found paid for expenses, but not their time. But since it was a fun hobby, that was OK.
Apparently, virtually all of the alluvial gold has been snatched up, though when I look at a map of Siberia… I have to wonder. But all the easy pickins’ in the US has long ago been cleaned up.
It must have been something - boulders of gold, in some instances.
Yes indeed. When I was a Boy Scout we would walk along the Sang Gabriel River in Southern California*, we would see flecks of gold in the sand on the riverbank. Met a few guys with pans also.
There is gold there, not much, but if you are doing it for a hobby, it could be fun.
*FTR gold as discovered in So Cal before Sutter’s Mill. “Placer gold was mined in the San Gabriel Mountains as early as 1834” cite
Any gold is a side benefit. 
You are certain to find enough to show dudes, and dudes still make an occassional lucky find. I had friends in Modesto that did this most every weekend, and what they found paid for expenses, but not their time. But since it was a fun hobby, that was OK.