Here is a link to a fellow who gets out and explores mines in the western States. Takes awhile to get around but there is some nice stuff.
http://www.starbuck.org/exploring/
Another site I found to be real neat is here...
http://www.ghosttownexplorers.org/ghost.htm
Don't miss the "baby gauge" fantastic 2ft gauge operation still in existance in Death Valley and the Borax underground workings there.
http://www.ghosttownexplorers.org/california/babygauge/babygauge.htm
I have been in Death Valley many times on my trips over the years and I sure am glad someone else suffered the extreme heat and thirst to hike in to take these wonderful pictures.
Chris.
in New Zealand.