I’ve seen YouTubes showing detectorists around those towns. They say the best places to find gold is in places it’s already been .found. The old timers went after the biggest and easiest to find and cheapest to mine deposits. But vastly improved detector tools and vastly higher prices increase the allure of gold. Nevada still has a lot of it.
Yes. Recovery methods 150 years ago were crude and they weren’t worried about improving recovery percentage. The tailings piles have lots of gold in them.