By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Deer Lodge County in southwestern Montana has produced large amounts of silver and both lode and placer gold. The total production of the county has not been accurately determined, for records of early production, especially placer production, were not kept. Although there was a large placer output in the 1860's and 1870's, the deposits were soon depleted and have been virtually dormant since 1900.
Production prior to 1904 was probably between $3.5 (169,330 ounces) and $8.25 million (399,135 ounces), of which about $2.5 to $3 million represents lode production and the remainder represents placer gold. From 1904 through 1952, the county produced about 303,000 ounces of lode gold and only 2,243 ounces of placer gold. The total minimum gold production of the county through 1959 was about 470,000 ounces.
Most of the gold mined in Deer Lodge County came from the Georgetown and French Creek districts. Georgetown yielded almost all the lode gold; French Creek yielded the placer gold.
FRENCH CREEK DISTRICT
The French Creek district is in southern Deer Lodge County about 12 miles south of Anaconda. The gold of the district came from placer deposits near the headwaters of French Creek and its tributaries. The total placer gold has not been ascertained, and the estimates of the early production vary considerably.
The deposits were discovered in 1864 and, according to Lyden (1948, p. 24), they were credited by R. W. Raymond with having produced about $1 million (48,380 ounces) to the end of 1869, but other estimates listed by Lyden (1948, p. 24) credited the district with a yield of $5 million during the same period. Between 1900 and 1902, a dredge and several hydraulic installations were operating in the district, but their productivity was not recorded.
The deposits were again worked in the 1930's, but only a few ounces of gold was recovered. The district was inactive from 1940 through 1959. Total gold production probably was between 50,000 and 250,000 ounces through 1959.
The Georgetown district, which includes the Cable mine and placer deposit, is in the northwestern part of Deer Lodge County in the upper drainage basin of Warm Springs Creek about 10 to 15 miles northwest of Anaconda and about 10 miles southeast of Philipsburg. Gold is the most valuable commodity mined in the district, but small amounts of silver and copper are also obtained. Virtually the entire output of lode gold of Deer Lodge County has come from the Georgetown district.
The Cable mine, the most productive in the district, was located in 1866, and a mill to treat the ore was built the following year (Emmons and Calkins, 1913, p. 221-222). The production of the mine to 1872 was worth about $400,000. In 1877, the mine changed ownership and a new mill was built. From 1877 until 1891, more than $2 million (96,760 ounces) in gold was recovered. The ore shoots were supposedly exhausted in 1891, and the mine closed. Under new management the mine was developed to deeper levels; additional ore was found and production was sustained for some time.
The Southern Cross mine, another large gold producer in the district, was also located in 1866, but the claim was allowed to lapse. It was relocated in the early 1870's, and ore worth a total of $600,000, mainly in gold, was mined intermittently through 1905 (Emmons and Calkins, 1913, p. 231). The lode mines were moderately active until 1943. Production ceased for the following 6 years, and only a few hundred ounces of gold was produced from 1950 through 1959.
Significant amounts of placer gold were mined in the early years, chiefly from the Cable placer, near the Cable mine, and from the Georgetown placers. The Cable placer was a bonanza deposit. In 1872 and 1873 it yielded $51,000 in gold, and it was worked for many years during which the total returns probably amounted to several hundred thousand dollars (Emmons and Calkins, 1913, p. 264).
The Georgetown placers, near Georgetown, produced about $40,000 (1,935 ounces) in gold in 1870. No other figures have been found covering placer production through 1934, and only 96 ounces was recorded from 1935 through 1959.
The total gold output of the district through 1959 was at least 460,000 ounces, most of which was from lode mines.
Faulted and folded sedimentary rocks, mainly of Paleozoic age, are intruded by a small stock and several smaller bodies of granitic rock (Emmons and Calkins, 1913, p. 221). The most productive mines are in the sedimentary rocks near the intrusive contacts, but some deposits are a mile or more from such contacts and some are in the intrusive rock. The deposits include gold-copper replacement deposits of contact-metamorphic origin, gold-bearing replacement veins in sedimentary rocks, and gold-bearing veins in granite (Emmons and Calkins, 1913, p. 221-242).
The chief ore minerals are pyrite, pyrrhotite, chalcopyrite, gold, and magnetite in a gangue of quartz, calcite, and garnet. The ore bodies at the Cable mine are large irregular replacement deposits in a large limestone block nearly surrounded by granite. In most of the other mines the ore deposits are chiefly replacement veins in limestone and calcareous shale.