By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Missoula County, in western Montana, at one time included several adjacent counties - Ravalli, Sanders, Lincoln, Mineral, and Lake - and parts of Granite, Powell, and Flathead Counties. Only a part of the gold production of Missoula County as reported in "Mineral Resources of the United States" (U.S. Geological Survey, 1904-23) prior to 1914 came from deposits within its present boundaries (Lyden, 1948, p. 103). Gold production of Missoula County has been chiefly from placer deposits in the Elk Creek-Coloma and Ninemile districts, but an appreciable amount has also come from lode deposits in the Elk Creek-Coloma district. The total minimum gold production through 1959 was about 150,000 ounces from placers and 20,000 ounces from lodes.
ELK CREEK-COLOMA DISTRICT
The Elk Creek-Coloma district is about 30 miles east of Missoula in the southeast corner of the county. Elk Creek rises in the Garnet Range, and the district lies on the north side of the range north of the famous mining camp of Garnet in the First Chance district in Granite County. Both lodes and placers were exploited for gold in this district.
Gold placers were discovered along Elk Creek about 1865 (Pardee, 1918, p. 231), and the early production of the district came from these deposits. Reliable figures on the early production are not available, but Pardee (1918, p. 232), judging from the extent of the old placer workings, estimated that the production must have been worth between $1 million and $2 million. After the first few years of frantic activity, the rich gravels were depleted; the boom was over. Most of the claims were abandoned, though a few were worked intermittently through the 1930's. Dredging operations from 1938 to 1940 yielded about 2,500 ounces. After 1940 and continuing through 1959 the placers were again abandoned. Gold lodes, discovered about 1867 in the Coloma area, were not developed until 1897. The Comet and Mammoth mines accounted for most of the early lode production. Both mines closed after a few years of operation, and the camp has been largely idle since then. About $250,000 in gold was produced from lode mines before 1916 (Pardee, 1918, p.195-196).
Total gold production of the district through 1959 was between 70,000 and 117,000 ounces. This included 52,000 to 100,000 ounces from placers; the remainder was from lodes.
The rocks in the Elk Creek-Coloma district are chiefly limestones of Paleozoic age and granodiorite of Late Cretaceous or early Tertiary age that intruded the limestone. Just west of Coloma the limestones are underlain by sedimentary rocks of the Belt Series (Pardee, 1918, p. 196-199, pi. 7). The veins are in granodiorite adjacent to limestone. Most of the ore was oxidized and was rich in gold. The sulfide ore, which is relatively low grade, is banded and consists of gold-bearing pyrite, chalcopyrite, and tetrahedrite with quartz gangue.
NINEMILE CREEK DISTRICT
Located in the northwest corner of Missoula County, Ninemile Creek is a tributary of Clark Fork River. Almost the entire gold production of this district has been from placer deposits along Ninemile Creek and its tributaries. The first discoveries were made in the district in 1874 (Lyden, 1948, p. 103). Some of the deposits were rich and several miles of placer ground was quickly located and patented (Lyden, 1948, p. 103-104). The amount of gold mined in this district prior to 1908 has not been ascertained but is reported to have been several million dollars (Lyden, 1948, p. 104). Placer operations along the creek were sustained for many years, but production declined sharply after 1915 and was intermittent in the 1920's. The pace of mining increased in the 1930's and, except for the war years of 1943-45, continued at a significant level through 1948. In 1954 dredging operations recovered 1,340 ounces of gold; otherwise the district was idle from 1949 through 1959. Total production through 1959 was probably between 100,000 and 125,000 ounces.
The gold-bearing gravels of the district are reported to be either in glacial till or glacial moraine (Lyden, 1948, p. 107). The gravel is cemented with clay and is difficult to break up, and although it is gold bearing, some of the deposits have yielded little or no profit. The source of the gold is probably the scattered gold veins in the mountains at the head of the creeks (Pardee, 1918, p. 234).
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