I only know from ground level, I have mined lots of quartz crystals but I ask you, show us an example but you can't, sat. images can't see at ground level.
Beach High Banker, Sweep Jig, Whippet Dry Washer, Lobo ST, 1/2 width 2 tray Gold Cube, numerous pans, rocker box, and home made fluid bed and stream sluices.
You might be able to pick out areas where there is slope failure/raveling with satellite photos and some of those areas may be caused by decomposing bed rock...You still need to check to determine rock type though.
Boots on the ground is about the only way, when you get close to the location a drone helps with locations, they see what you will never find without walking on top of it.