Carbonate-Hosted Au-Ag-Pb Deposits, Northern Black Hills
Montri Wimonrat, Colin J. Paterson, 1990. "Carbonate-Hosted Au-Ag-Pb Deposits, Northern Black Hills", Metallogeny of Gold in the Black Hills, South Dakota, Colin J. Paterson, Alvis L. Lisenbee, Tommy B. Thompson
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The Carbonate and Ragged Top mining districts, located about 5 miles northwest and west of Lead respectively, are the only two areas in the northern Black Hills where significant replacement deposits of silver-lead and gold-silver occur in the Mississippian Pahasapa Limestone (Fig. 1). There is an additional occurrence of weakly- mineralized Pahasapa Limestone in the Vanocker area, SE of Lead (Fig. 1). Following discovery of high grade silver- lead ores in 1881, Carbonate became a flourishing mining camp from 1885 to 1891 with a total production of at least 2.6 kg (83 oz) of gold; 525 kg (18,511 oz) of silver; and 5,193 kg (183,191 lbs) of lead (Shapiro and Gries, 1970). At Ragged Top (Fig. 1), after gold was discovered in 1896, mining operations were continuous until 1917, producing a total of 1,879 kg (60,598 oz) of gold (Shapiro and Gries, 1970). From 1937 to 1958, the deposit was sporadically exploited and was finally abandoned. Current mining and heap-leach processes make the Carbonate and Ragged Top areas favorable for renewed exploration.
In the Carbonate district, the Pahasapa Limestone has been intruded extensively by early Tertiary sills and dikes. The principal ore bodies are of two types: fissure veins and solution cavity-filling. Fissure veins consist of Au- bearing ferruginous gouge in the center and Pb-Ag rich (galena, cerussite, and cerargyrite) jasperoids along the margins (Irving, 1904). The solution cavity-filling ores are usually close to igneous intrusions, are less siliceous than jasperoid and are rich in lead, silver with minor gold