Finding Mines in the Desert
There are many abandoned gold and silver mines in the desert southwest. Most "played out" where there was no longer any ore worth processing, but some were closed when the price of gold or silver dropped. Roads and trails generally go somewhere, in mining areas the remains of such roads often go to mines. Sections can look in quite good shape, and other parts will have plants growing in them or be completely washed out.
Tumco, California is an example of a gold mining area. You can wander the hills and find mine shafts, tunnels, and collapsed mine shafts. Some have fences, most of which are in poor shape.
Castle Dome, Arizona was a silver mining area. Kofa NWR does not allow new mining claims, but some of the ones that existed when it was created have been maintained. Roads marked "No Vehicles" lead to many of the mine shafts that have been abandoned.
Palmetto, Nevada is another silver mining area. I did not explore the area around it much, but the land is BLM land open to exploration and possibly filing mining claims.
Tonopah, Nevada managed to survive past the silver mines closing, and is now a town at a highway crossroads. The mining park in Tonopah is well worth a visit if you are interested in mining history.