Hello - I wish I could be of help, but I sent off all the material to another researcher. Shortly afterward my computer 'blew' and I lost all my contact information. But I do vaguely remember that this researcher was connected to an Historical Society or something of that nature. Whether the specific connection was to the mining company or to P. M. Clarke, I'm not sure. It's my sense it was the Montana Mines Company that was the draw rather than Mr. Clarke - but I can't guarantee it.
I wish you good luck! This summer I'll be back down to Goldfield, Nevada area and will stop in at that little, old antique store to see if they have additional treasures.
Best of luck with your research - Sue firstname.lastname@example.org