Principal Gold-Producing Districts of The United States
HISTORY OF GOLD MINING AND TRENDS IN PRODUCTION
Gold in the United States was first mined in the Southeastern States about 1799, but these deposits, in the mountainous areas of the United States,. though rich, were relatively small. After the discovery of placer gold in California in 1848, the Western States contributed the bulk of the domestic gold production. Placer deposits offered quick and large returns with simple equipment and thus stimulated migration to the new gold fields. Many prospectors, trained in the California gold fields, spread to other parts of the new territories and many deposits were found in rapid succession in widely separated areas. The discovery of these rich placer deposits marked the beginning of active development and settlement of the West. Exploration and mining activity boomed; gold production reached 2 million ounces in 1850 and 3 million ounces in 1853. It then declined steadily and in 1862 again dropped below the 2-million-ounce level. Placers were the chief source of our domestic output until 1873 (Loughlin and others, 1930, fig. 3), when their output was exceeded by that of lode mines, a relation that has continued through 1965. Placer activity remained at a relatively low ebb during the production from this district together with the in 1880’s and early 1890’s, but there were three periods in later years when placer production, though exceeded by lode production, formed a significant proportion of the domestic output – in 1896 when large dredges were introduced in California, in 1904 when large deposits of rich gravels were discovered in Alaska, and in 1934 when the price of gold was increased to $35 an ounce.
In many districts the prospectors followed gold- bearing gravel to the source of the gold in veins, and lode mining began shortly after placer mining. It wa not, however, until about the middle 1860’s, when the Mother Lode and Grass Valley lodes in California and the Comstock Lode in Nevada became important producers, that lode mines became significant sources of gold. Lode production increased rapidly after the discovery of gold in the Cripple Creek district, Colorado, in 1892. By 1898, production from this district together with the increased placer production in California and the accelerated output of the Homestake mine at Lead, S. Dak., had raised our annual gold production to more than 3 million ounces. Production continued to rise with the discoveries of gold at Tonopah, Nev., in 1903, the placer deposits of Alaska in 1904, and gold at Goldfield, Nev., in 1905. By 1905 gold production for the first time exceeded 4 million ounces, a level maintained until 1917. Because of a shortage of manpower during World War I, production then declined rapidly, falling almost to the 2-million-ounce level by 1920, where it remained until 1934. Many gold mines were reopened during the depression in the early 1930’s. When the price of gold was raised in 1934 from $20.67 to $35 per ounce, production increased rapidly and in 1937 again passed the 4-million-ounce mark. Additional gold was obtained as a byproduct from increased output of base metals in the late 1930’s, and in 1940 gold production reached an alltime high of 4,869,949 ounces. Shortly after the United States entered World War II, the gold mines were closed, and gold production in 1944 and 1945 dropped below the 1-million-ounce mark, the lowest since 1849. Production in 1965 was 1,705,190 ounces.
From 1907 until 1943 byproduct gold, obtained from base-metal ores, formed a small, though significant, fraction of the total production of this country. Only in World War II (1943-45 inclusive), when base-metal production increased and gold mines were closed, did byproduct gold contribute more than 50 percent of our annual domestic pro- duction, and since 1951 it has steadily outranked placer production. Most of the byproduct gold is recovered from porphyry copper ores. Large-scale copper mining at Bingham, Utah, has yielded suffi- cient gold to put this district in second place in an- nual gold production in recent years. The Lead dis- trict, South Dakota, has had the greatest total gold production and was also the largest producer in th€ United States each year from 1946 through 1965.
In an analysis of gold-production trends, the pe- riod 1932-59 is particularly informative because it reflects the most flourishing and the most adverse periods of gold mining in the United States. A long period of desultory activity ended in 1934 when the price of gold was increased from $20.67 to $35 per ounce. Mines were opened that had been closed for decades, and the gold-mining industry experienced an unprecedented interval of prosperity. This was ended in 1942 by the imposition of War Production Board Order L–208 (U.S. Bureau of Mines, 1943, p. 80-84), which resulted in most of the gold mines closing for the duration of World War II. After World War II, the gold-mining industry, plagued by constantly rising costs under a fixed selling price, failed to experience the growth and robust activity enjoyed by most industries. Thus, gold mining has been somewhat paradoxical-it reached its zenith in an economic climate unfavorable to most other industries, and it declined sharply when industrial growth was accelerating.
Of the 508 principal districts, in 1959 about 400 were either dormant or had an annual production of less than 100 ounces. Of the 25 leading districts (listed in fig. 2), 8 are dormant, 5 produce less than 100 ounces annually or have sporadic production, and only 12 of them maintain activity comparable to that of the prewar period.
Gold discoveries in Georgia stimulated interest in prosP€cting similar-appearing crystalline rocks of Alabama and by about 1830 the first discoveries were made (Adams, 1930, p. 8). In the 1830’s and 1840’s, thousands of people were working the de- posits at Arbacoochee and Goldville, but this boom collapsed when the California placer discoveries lured away most of the miners. Gold mining continued at a subdued pace that was broken by accel- erated activity in 1874, when copper fever gripped the State, and in 1904, when cyaniding was intro- duced at Hog Mountain (Adams, 1930, p. 10). The increased price of gold in 1934 caused another spurt of activity, but during the late 1940’s and the 1950’s mines were closed once more. Gold production of Alabama from 1830 through 1959 was 49,495 ounces (fig. 3).
The belt of gold-bearing gneisses and schists extends from Georgia into east-central Alabama, where it is overlain by gently dipping unmetamor- phosed sedimentary rocks of the Gulf Coastal Plain. The gneisses and schists are bordered on the north- west by the folded Paleozoic sedimentary rocks that form the southern end of the Appalachians, which become more subdued and are covered by the Coastal Plain sediments in the southwestern and western parts of the State. The gold deposits occur in the Talladega Slate, the Hillabee Chlorite Schist, the Wedowee Formation, and the Ashland Mica Schist. The ages of these rocks are not clearly de- fined. Butts (in Adams and others, 1926, p. 59-61) considered the age of the Talladega as ranging from Precambrian through much of the early Paleozoic. Adams (Adams and others, 1926, p. 32-33, 37) assigned a tentative Cambrian to Carboniferous age to the Wedowee Formation, and he considered the Ashland Mica Schist to be Precambrian in age. Intrusive into these metasedimentary rocks are the metaigneous Hillabee Chlorite Schist and the Pinckneyville Granite, both considered post-Carbonifer- ous in age by Adams (1930, p. 17, 18). Most of the gold deposits are in Cleburne, Tallapoosa, Clay, and Randolph Counties, but only two districts have pro- duced more than 10,000 ounces of gold-the Arba- coochee district in Cleburne County and the Hog Mountain district in Tallapoosa County.
The Arbacoochee district, in southern Cleburne County in Tps. 16 and 17 S., Rs. 11 and 12 E., con- tained the richest placers of the State; it was ex- tremely active in the 1830’s, but by 1874 only a few miners were still at work there (Adams, 1930, p. 21). Several attempts at lode mining were made in the late 1800’s, but by 1900 these mines were idle (Adams, 1930, p. 22, 23).
Brewer (1896, p. 85) credited the Arbacoochee district with most of the $365,300 in gold (17,700 ounces) produced by Alabama to 1879; after 1890 this district became almost inactive and the Hog Mountain district became the State’s principal producer.
Most of the gold came from residual placers in the vicinity of Gold Hill and from gravels along Clear Creek (Adams, 1930, p. 21-22). Bedrock in the southern part of the district consists of Ash- land Mica Schist and in the northern part, of rocks of the Talladega Slate. These two units are separated by a band of Hillabee Chlorite Schist which was intruded along an old thrust fault plane (Adams, 1930, p. 18). Gold-bearing quartz veins with pyrite occur in the Hillabee, but they are too low grade to be economic.
In Tallapoosa County the principal gold producer was the Hog Mountain district, in the north-central part of the county in T. 24 N., R. 22 E.
The only workings of any consequence in this dis- trict are those of the Hog Mountain or Hillabee mine, which opened in 1839 and operated on a small scale until 1893, when larger ore bodies were dis- covered and production increased. From 1893 to 1916, the mine produced $250,000 (about 12,100 ounces) in gold (Adams, 1930, p. 50). The mine was closed in 1916 because of high operating costs and was not reopened until 1933. During 1934-37 the Hog Mountain mine was the largest producer in Alabama, but it was closed in 1938 and remained inactive through 1959. Total gold production of the district through 1959 was about 24,300 ounces, about half of which was produced during 1934;_37.
Bedrock in the Hog Mountain district consists of schistose rocks of the Wedowee Formation and quartz diorite· (Park, 1935, p. 4-6). The schist is dark gray, graphitic, and is complexly folded and may be cut by thrust faults. The age of the Wedowee was considered by Adams (1930) to range from Cambrian to Carboniferous, but Park (1935, p. 5) thought it might even be Precambrian. The quartz diorite, which may be related to the_Pinckneyville Granite of post-Carboniferous age, intruded the deformed Wedowee Formation. The larger gold veins of the district fill shear zones in the quartz diorite. Quartz is the most abundant vein mineral ; pyrrhotite and small amounts of chalcopyrite, py- rite, arsenopyrite, gold, sphalerite, galena, bismuth minerals, and silver (Park, 1935, p. 12, 13) also occur.
Source: Principal Gold=Producing Districts of the United States
by A.H. Koschmann and M.H. Bergendahl
Geological Survey Professional Paper 610
U.S. Department of the Interior