Economic geology of the Central City district, Gilpin County, Colorado

Economic geology of the Idaho Springs district, Clear Creek and Gilpin Counties, Colorado

“…Most of these occurrences are on or near the southsouth westward projection of the conspicuous fault; however, the Torpedo mine is more than a mile to the west. The gold telluride ores were formed Jater than the principal sulfide ores, as interpreted by Levering and Goddard (1950, p. 174, 187); Bastin and Hill (1917, p. 114);and Sims, Drake, and Tooker (1963).…”

“…Excellent summaries of milling and smelting practices are given by Bastin and Hill (1917, p. 153-163), and by Sims, Drake, and Tooker (1963).…”

“…The pattern is also denned by carbonate gangue that increases in amount radially from the core area, by barite that increases from the peripheral zone outward, and by average silver-gold ratios that increase radially. Details of this zonal pattern are given by Sims, Drake, and Tooker (1963) and by Sims and Barton (1962). The zonal pattern in the Idaho Springs district is less well defined and is not concentric.…”

“…From 1904 to 1959 inclusive the ore production from the Idaho Springs district (together with some of the mines outside the district) was valued at $14,987,314 (table 1), but the total production since mining began in the Idaho Springs district was far greater. From 1859 to 1903 the ore production from Gilpin County was valued at about $81 million (Bastin and Hill, 1917, p. 174-175;Sims, Drake, and Tooker, 1963), or about 3i£ times the post-1903 production. The same ratio of pre-1903 to post-1903 production applied to the Idaho Springs district gives it a total production valued at about $65 million.…”

“…The Freeland-Lamartine district and the Chicago Creek area, southwest of the Idaho Springs district, were studied by Harrison andWells (1956,1959). The Lawson-DumontFall River area to the west was studied by C. C. Hawley and F. B. Moore, and the Central City district to the north was studied by Sims, Drake, and Tooker (1963). Specialized studies of the uranium deposits (Sims, Drake, and Tooker, 1963;Sims and others, 1963;Sims and Sheridan, 1964), Tertiary igneous rocks (Wells, 1960), and wallrock alteration (Tooker, 1963) were also made.…”