By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Park County, in southern Montana just north of Yellowstone Park, was organized in 1887. Gold placers were discovered in the area as early as 1862 near Gardiner, and by 1870 gold-quartz veins were found near the present site of Jardine and in the Cooke City district. The history of mining in the county is punctuated by brief periods of development and longer intervals of decline, litigation, and idleness (Reed, 1950, p. 7-9).
Mineral production prior to 1887 is estimated at not more than $500,000, a large part of which was in gold. From 1887 through 1947 the county produced 250,513 ounces of gold (Reed, 1950, p. 10, table 5) and from 1948 through 1959, about 22,660 ounces. Total gold production through 1959 was roughly 295,000 ounces, more than half of which was mined from 1933 to 1953. The Emigrant Creek, Jardine, and Cooke City districts have been the major sources of gold in Park County.
EMIGRANT CREEK DISTRICT
Emigrant Creek is a tributary of Yellowstone River, which it joins about 24 miles north of Gardiner. The date of discovery of ore deposits in the Emigrant Creek district has not been ascertained, but gold lodes in the district were worked in the 1870's (Reed, 1950, p. 52). The lodes, however, never were economically important. The earliest placer production records date back to 1901 (Reed, 1950, p. 14). Prior to 1941 these gravels were worked in drift mines, or with hydraulic giants, or by ground sluicing. In 1941 a large bucket dredge was assembled on Emigrant Creek and was operated until October 1942.
In April 1946 these operations were again resumed, but they were unsuccessful because of increased mining costs. The district remained dormant through 1959. These placers accounted for one-half to two-thirds of the annual production of placer gold in the county (Lyden, 1948, p. 110). Total placer production from 1901 through 1959 was 15,606 ounces. During 1901-3 the district also produced 395 ounces of lode gold (Reed, 1950, p. 14).
The placer gold was derived from the mineralized area at the headwaters of Emigrant Creek (Reed, 1950, p. 50-54). The country rock consists of Pre-cambrian granite, gneiss, and schist, Paleozoic sedimentary rocks, and Tertiary volcanic and intrusive rocks. Small quartz stringers and veins containing galena, sphalerite, pyrite, and chalcopyrite, and small amounts of gold are found in the volcanic rocks, although a few deposits are in the Precam-brian rocks. A few veins are valued chiefly for molybdenite and also contain small amounts of gold and silver.
The Jardine (Sheepeater) district is 6 miles east of Gardiner in the southern part of Park County. Gold and arsenic are its major products; tungsten has been recovered as a byproduct of gold mining.
Placer gold was discovered in the gravels along Yellowstone River near Gardiner in 1862 and near the mouth of Bear Gulch in 1866; a search for its origin led to the discovery in 1870 of gold-quartz veins at the present site of Jardine (Reed, 1950, p. 7). The early activity in the district consisted chiefly of placer operations, which produced only small amounts of gold. Little development was done on the lodes until 1884 when completion of a five-stamp mill ushered in a period of successful lode mining that lasted until the panic of 1893 (Seager, 1944, p. 6-7).
From 1893 to 1902 activity was intermittent and production was relatively small. Mining activity during 1902-42 was interrupted by an extended period of litigation from 1909 to 1916 and by a shutdown from 1926 to 1932 (Reed, 1950, p. 8). Operations were temporarily suspended in 1942 because of the Federal restrictions on gold mining, but increasing war demands for arsenic led to the reopening of the mines, which operated until May 1948, when fire destroyed the cyanide plant. There was no recorded production from 1948 through 1959.
The recorded gold production from the Jardine district from 1902 through 1947 was 174,888 ounces, including 407 ounces of placer gold (Reed, 1950, p. 11). The district produced an additional 6,498 ounces of lode gold in 1948. The total gold production through 1959 was probably between 190,000 and 200,000 ounces.
The Jardine district is underlain by a complex of schist and quartzite intruded by masses of granitic rocks, all of Precambrian age. These are overlain by Paleozoic and Mesozoic sedimentary rocks and Tertiary volcanic rocks. The ore deposits are in the Precambrian schist and are the only gold deposits of Precambrian age in Montana (Seager, 1944, p. 43). In many respects these ore bodies are similar to the gold deposits in the Homestake mine, South Dakota (Seager, 1944, p. 43).
The ore deposits are in veins of two mineralogic types: quartz veins in quartz-biotite schist, and arsenopyrite (sulfide) veins in quartz-cummingtonite schist. The quartz veins are the more abundant. Both types of veins are replacements of country rock rather than fissure fillings; as a result, they are characteristically uneven in thickness, continuity, and grade, and although parallel in general with the foliation, a few veins crosscut foliation (Seager, 1944, p. 44-45).
The most common ore minerals in the quartz veins in the quartz-biotite schist are arsenopyrite, pyrite, galena, gold, and scheelite. The arsenopyrite veins in the cumming-tonite schist have a much higher and more uniform sulfide content and contain more gold and less tungsten than the quartz veins. They also are the chief source of arsenical ore. These veins contain variable amounts of pyrite, pyrrhotite, and gold in addition to arsenopyrite (Seager, 1944, p. 48-50).
COOKE CITY DISTRICT
Located in the southeast corner of Park County, the Cooke City (New World) district has produced silver, copper, lead, and zinc ores from which small amounts of gold have been recovered as a byproduct.
Rumors of rich lead, silver, and gold deposits in the New World district were reported as early as 1868, and in 1869 trappers, fleeing from an Indian raiding party, discovered a manganese-stained outcrop on the property which was later developed as the Republic mine. In 1870 the first claims were located in the district, although it was still part of the Crow Indian Reservation (Lovering, 1930, p. 44). A furnace was built in 1875, and lead ore was smelted until an Indian raid in 1878 terminated these efforts.
In April 1882 the district was withdrawn from the Crow Indian Reservation and opened to settlement (Lovering, 1930, p. 45). This resulted in increased mining in the district, and a lead smelter and roasting furnace were erected. However, high freight rates prevented any extensive development, and finally the Republic mine, the most productive in the district, and the smelter were closed in 1887. Only sporadic exploration continued, resulting in small production of gold ore in the early 1890's (Lovering, 1930, p. 46).
From 1904 through the 1920's several properties in the district were mined for short periods, but most of these operations ended in failure; only high-grade lead-silver ore was shipped (Lovering, 1930, p. 46-47). In 1933 a concentrator was built that successfully treated low-grade pyritic gold-copper ores (Reed, 1950, p. 8-9). This activity continued through 1953, and small-scale lead-silver mining was carried on through 1957.
Early production statistics are not available but, according to Lovering (1930, p. 48), smelter records show that 438 ounces of gold was recovered in 1886 in addition to considerable amounts of silver and lead. From 1901 through 1932 only 270 ounces of byproduct gold was produced (Reed, 1950, table on p. 12). Gold recovered from 1933 through 1959 amounted to 65,245 ounces. Total gold production of the district through 1959 was at least 66,000 ounces.
The Cooke City mining district is on the southwest flank of the Beartooth-Snowy Mountain anticlinorium. Granite, gneiss, and basalt porphyry of Precambrian age are exposed in the central part of the structure. Overlying the Precambrian rocks are sedimentary rocks of Cambrian, Ordovician, Devonian, and Carboniferous age. After these rocks were folded into the large anticline and erosion had modified the relief, Tertiary lavas and pyroclastics covered the surface, and plugs, stocks, dikes, and sills of gabbro, porphyritic quartz monzonite, grano-diorite, diorite, syenite, and basalt intruded the rocks (Lovering, 1930, p. 12-40).
The district contains a variety of ore deposits, most of which are clustered around two stocks - one of quartz monzonite and the other of syenite. Mineralogically, the deposits can be classified into copper-platinum, copper-lead-gold, pyritic copper, gold-quartz, copper-lead, lead-silver, lead-zinc-silver, carbonate-silver, and gold placers. Most of the gold has come from the pyritic copper deposits which were exploited from 1933 through 1953. These are veins containing quartz and pyrite and smaller amounts of chalcopyrite, galena, and sphalerite. In the higher grade ore, the value of gold ranges from $5 to $15 per ton (Lovering, 1930, p. 49-52).
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