Gunnison County Colorado Gold Production
In the Tincup district in northeastern Gunnison County, about 25 miles northeast of Gunnison, gold has been obtained mainly as a byproduct of silver-lead ores, although a considerable amount has come from placers. Most of the mines are at the head of Willow Creek on the southeast side of Taylor Park.
One of the first reported gold discoveries in the county was in 1861 when a man named Taylor, searching for strayed horses, found good color in what became known as Tincup Gulch. During the next 18 years there was sporadic placer mining in Tincup Gulch. In 1879 the lode source of the placer gold was found, and soon miners streamed into the area. The town of Tincup had a population of nearly 4,000 by the end of 1880. The boom lasted until the price of silver dropped in 1893. A second period of prosperity began in 1904, which attracted about 2,000 people to the district. This was short lived, and by 1912 the mines were again inactive (God-dard, 1936, p. 552-554). From 1912 through 1959 the district was virtually idle; even the increased price of gold in 1934 did not renew activity.
Total gold production of the district through 1959 was about 16,400 ounces, most of which was produced before 1932.
The rocks exposed in the Tincup district are of three ages: schist and granite gneiss of Precambrian age, sedimentary rocks about 1,000 feet thick of Paleozoic age, and intrusive rocks of Tertiary age. The Paleozoic rocks are chiefly limestone, with some shale and quartzite, and range in age from Cambrian to Pennsylvanian. The Tertiary rocks consist of quartz monzonite porphyry and hornblende diorite porphyry which form dikes, sills, and a stock. The rocks were folded into a north-trending monocline that dips to the east. Along the east side of the district, the sedimentary rocks are in contact with the Precambrian schist along the Tincup thrust fault that trends about N. 25° W. Another strong thrust of the same trend appears in the southwest part of the district. Numerous small high-angle faults, younger than the thrusts, cut the rocks (Goddard, 1936, p. 557-565).
The most productive ore deposits have been silver-lead-gold blanket deposits and silver-lead-gold veins. Of slight importance are molybdenum-tungsten veins and iron blanket deposits. The metals produced, in the order of their value, are silver, lead, gold, and small amounts of copper. The blanket deposits have been the most productive. These occur at the contacts between limestone and dolomite near intersections with steeply dipping faults or fractures. The chief primary ore minerals are silver-bearing galena and pyrite and small amounts of chalcopyrite and sphalerite. The gold is probably associated with the pyrite. The chief gangue minerals are quartz and calcite. All the ore of the blanket deposits is at least partly oxidized, and much of the ore consists of cerussite and anglesite, usually associated with some galena, in a limonitic and siliceous gangue. Oxidation of the ore bodies extends to a depth of more than 500 feet.
The vein deposits, which cut the Precambrian granite gneiss and the sedimentary rocks, range from 1 to 6 feet in width and from 600 to 1,000 feet in length. The minerals and character of the ore are similar to those in the blanket deposits (Goddard, 1936, p. 565-569).