We spent a weekend in SW Montana last summer and we could have spent a couple weeks exploring this area.
We went to a old mining ghost town outside of Phillipsburg named Hasmark ( N46 19.998 W113 16.055 ). It was somewhat winding drive up a mountain side.
We also had a BUNCH of fun at a place called Gem Mountain http://www.gemmtn.com - we had so much fun here. This is a sapphire mine and the owners of the mine sell concentrate from the mine where you and the family can buy buckets of gravel, wash it and hopefully find sapphires.
I found a 3.5 carat sapphire. I had it treated and cut (finished 1.12 carat) ans it was appraised at $600.00. We also found 23 carats of cuttable stones. So all and all it was a great weekend.
Since we are new to geocaching we thought perhaps on our first hide we would include a couple sapphires from that trip.
Anyway, there is a book by Barbara Fifer called Montana Mining Ghosttowns. It would be a great reference for you.
