By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Granite County, in west-central Montana, through 1959 produced a total of 710,000 ounces of gold - 376,000 ounces from silver lodes and 334,000 ounces from placers. The most prosperous period was 1881-93 when the Granite Mountain, Hope, and a few other silver mines were at their peaks. Most of the lode gold has been a byproduct of silver ores in the Flint Creek, First Chance, and Boulder Creek districts (Emmons and Calkins, 1913, p. 192).
Placers along Bear Creek in the First Chance district and along Henderson Creek in the Henderson district were also productive, mostly before 1900. Lodes and, to a lesser extent, placers continued to yield substantial amounts of gold until 1946, but their output diminished through the 1950's.
BOULDER CREEK DISTRICT
The Boulder Creek district is in the east-central part of Granite County, about 7 to 9 miles northeast of Philipsburg. Most of the gold has come from lode deposits that also yielded some silver, lead, and copper. There were intermittent placer operations along Boulder Creek and its tributaries through 1942, but production from these was small (Lyden, 1948, p. 40-41).
Although lode deposits were found in districts surrounding the Boulder Creek basin in the 1860's, important discoveries were not made on Boulder Creek and its tributaries until 1885 (Emmons and Calkins, 1913, p. 192). The district was active until 1906 when the Royal mine, the most productive in the district, was put under lease (Emmons and Calkins, 1913, p. 246-247) and thereafter activity declined. Production again increased during the 1930's after the price of gold was raised, but from 1943 through 1959, activity was minor.
The early lode production is not known. The Royal mine is credited with a production, principally in the late 1890's, of about $1 million (48,379 ounces) in gold, and a small production came from other mines (Emmons and Calkins, 1913, p. 246). Total gold production of the district through 1959 was about 58,450 ounces, including about 1,400 ounces from placers.
The country rock in the Boulder Creek district consists of extensively faulted and tilted sedimentary rocks ranging in age from Precambrian to Mesozoic and biotite granite of Tertiary age which intruded the sedimentary rocks. Some of the faults cut the granite. The ore deposits are chiefly fissure veins in the granite, in siliceous Precambrian rocks, and in Carboniferous or Mesozoic quartzite and impure limestone. A few replacement veins are in relatively pure Paleozoic limestone. The most productive deposits are gold veins that contain small amounts of silver. A few veins are silver or silver-lead veins that contain a little gold. The principal sulfides of the gold ores are pyrite and galena in quartz gangue; the silver ores carry also tetrahedrite and sphalerite (Emmons and Calkins, 1913, p. 246-250).
Page 1 of 4