Geology and Mines of the Upper Blackfoot Valley, Montana

The purchase and continued operation of the Mike Horse mine in the Heddleston district, by the American Smelting and Re­fining Company, gives the Blackfoot Valley a renewed promise of a prosperous future in its role as a mining district. In the past, large amounts of placer gold were recovered from the gulches of the area, however, because of the transporta­tion facilities, only the upper portions of a few lodes were exploited by the early miners.

An Isopach Map and a Discussion of the Cambrian Strata in the Central Cordilleran Area

In the past few years intensive studies have been going on concerning Cambrian formations as a locale for orebodies. Many of the dolomites and limestones of southwestern Montana are susceptible to replacement by mineralizing solutions, especially when overlain by a rather impervious layer of shale, as is the Pilgrim limestone of Upper Cambrian time.