5 Crushed Stone, Dimension Stone, Landscape Stone, and Industrial Mineral Resources of the Southeastern United States

Thursday, 19 March 2015
8:00 AM - 12:00 PM
Roberts

HAMME (TUNGSTEN QUEEN) MINE TAILINGS, VANCE COUNTY, NORTH CAROLINA: MINERAL CHEMISTRY OF POTENTIALLY RECOVERABLE HUEBERNITE-WOLFRAMITE AND SULFIDE MINERALS

Paper number: 5-5
Program: Theme Sessions
Time: 9:10 AM – 9:30 AM

Authors

Abstract

The Hamme (Tungsten Queen) mine, Vance County, N.C., was worked for wolframite-huebnerite and also produced minor amounts of sulfides (copper and silver). There are about 1 million metric tons of quartz-dominated tailings containing about 0.25% WO3, with accessory fluorite and very minor sulfides – mostly galena with accessory silver values. Tungsten prices are currently high (~$310/mtu WO3). This is an outgrowth of a statewide study of mine tailings by the NCSU Minerals Research Laboratory.

This study reports preliminary mineral chemistry of huebnerite, fluorite, and accessory sulfide minerals in the mine’s tailings piles. All minerals investigated have concentrations which show very limited compositional ranges. Huebnerite is strongly enriched in WO3 (73.5-75.5 wt. %), MnWO4 (97.3-99.7%, and Mn (1.037-1.065 atoms per formula unit, apfu) but is depleted in Fe2+ (0.040-0.029 apfu). Sulfide mineralogy is comprised of chalcopyrite with concentrations of Cu (33.8-38.2 wt. %), Fe (29.7-29.9 wt. %), and S (34.5-34.6 wt. %) and galena with concentrations of Pb (83.0-85.8 wt. %), S (13.2-13.9 wt. %). Lead in Hamme Tungsten deposit is comparable in S concentrations to other deposits; however, Pb concentrations are lower. Hamme tungsten deposit huebnerite compositions reported here are comparable (although slightly enriched in Mn but depleted in Fe2+) to other huebnerite deposits such as Round Mountain in Nevada and some huebnerites from Portugal. Compared to other wolframite deposits, the Hamme tungsten deposit is more depleted in Fe2+ and highly enriched in MnWO4, an indication of a lack of the substitution of its Mn by other cations. Potentially economic minerals in the mine’s tailings include wolframite-huebnerite, the quartz ‘sand’ that comprises the bulk of the tailings for specialized applications, fluorite for cement and/or glass manufacture, and potential credits of silver from the galena.