Thanks for looking Jag. It would not have to be a US traded company as most foreign stocks will have a pink sheet equivalent (reuters.com gives other exchange listings on foreign stocks). There must be some public company providing specialty equipment just for exploration?
I actually bought some SILXF.PK earlier this year (proof that I can make any stock go down just by buying it). They also offer SILXY.PK for 4x the price but not sure of the advantages.
I am new to the ADR's but if I understand it correctly you also end up trading the currency exchange along with the stock because the value is based on the foreign currency (but lately that would be a good thing). If anyone has a good broker for getting a good prompt fills on PK stocks without large fees, I would be interested.