Last updated Nov 16, 2018
Idaho State Historical Society Reference Series
Number 824 1980
Responsible for Idaho’s final gold rush, Thunder Mountain had antecedents which went back to an earlier era. Early day prospectors radiating out from Warrens after 1862 were attracted by Thunder Mountain’s conspicuous mineralization, and wild tales of early investigation there circulated after 1899. Other accounts had greater accuracy. James W. Pie, a prominent Lewiston pioneer of 1861, had discovered a good Thunder Mountain outcrop with free gold in 1866 or 1867. That led him to search “for the placer ground that would apparently go with the rich quartz lead. But the country was then the summer stamping ground of the Sheepeater Indians, who about this time became troublesome, and white prospectors were compelled to leave.” Poe reported that Chamberlain Basin miners also had to evacuate because they could not process gravel worth less than twenty-five cents a pan in 1867. While on a trip to Buffalo Hump in 1899, Poe returned to Thunder Mountain only to find that his old discovery had been taken up during an early phase of mining development there. Poe was fortunate not to get too involved in Thunder Mountain lode properties, although some of his unpromising 1899 claims there were later relocated and sold to Pittsburgh investors.
Although Poe could make no use of an almost inaccessible gold lode at Thunder Mountain in 1867, mining conditions improved in three decades. Ben and Lou Caswell-twin brothers from Michigan who had learned something about prospecting in Colorado–had searched for Seven Devils mineral wealth with no success at all in 1894. During the Panic of 1893, gold mining was favored over copper, and they decided to hunt for gold in as remote a wilderness as they could find. By then they were broke. The way Ben reported it, all they “had was a bunch of scrawney cayuses–in fact they represented about our only possessions when we went into the Seven Devils, so we can’t say we lost anything there. Finding some good surface indications on Thunder Mountain in August of 1894, they settled on Cabin Creek, trapped and hunted for a living, and came back the next two summers to use rockers during short two-week seasons when placering was practical. They recovered $245 worth of gold in eight days in 1895 and another $190 in 1896. In 1896 they spent most of their time whipsawing lumber for sluices, so as to increase future production. Then their brother Dan and his partner, Wesley Ritchie, came over from Montana to join them in producing $900 in 1897 with sluices. Encouraged with this success, Ben and Lou came out to Boise, August 10, with a remarkable story:
That there are Klondikes yet hidden from the knowledge of men in the wilds of the Idaho mountains was demonstrated yesterday when the discoveries of A. B. and L. G. Caswell in the Salmon River country became known.
These men came into town with a large clean-up of gold. When asked about their discovery they stated they mined the gold on what they called Mule Creek, which heads in a mountain which they named Thunder Mountain. Mule Creek flows into Monumental Creek, this into Big Creek and Big Creek into the Middle Fork of the Salmon.
The brothers discovered the claims some four years ago. The first three seasons they made expenses and this year they have secured a fine clean-up. They expressed the belief that the district will make a good camp; and from their report of the character of the discovery would seem to be well founded.
They have been placer mining the surface of lode claims, working the debris on the mountain side. The entire mountain, they say, is gold-bearing and the gold they have been getting has been released by the decomposition of the formation over which it is found.
This remarkable mountain is porphyry. The prospectors describe it as being a great volcanic crater which has been filled with the fold-bearing rock. The gold is found everywhere on the mountain.