Geochemical and Mineralogical Characterization of the Abandoned Valzinco (Lead-Zinc) and Mitchell (Gold) Mine Sites Prior to Reclamation, Spotsylvania County, Virginia

By Jane M. Hammarstrom, Adam N. Johnson, Robert R. Seal II, Allen L. Meier, Paul L. Briggs, and Nadine M. Piatak

The Virginia gold-pyrite belt, part of the central Virginia volcanic-plutonic belt, hosts numerous abandoned metal mines. The belt extends from about 50 km south of Washington, D.C., for approximately 175 km to the southwest into central Virginia. The rocks that comprise the belt include metamorphosed volcanic and clastic (noncarbonate) sedimentary rocks that were originally deposited during the Ordovician. Deposits that were mined can be classified into three broad categories:

1. volcanic-associated massive sulfide deposits,
2. low-sulfide quartz-gold vein deposits,
3. gold placer deposits, which result from weathering of the vein deposits

The massive sulfide deposits were historically mined for iron and pyrite (sulfur), zinc, lead, and copper but also yielded byproduct gold and silver. The most intensely mineralized and mined section of the belt is southwest of Fredericksburg, in the Mineral district of Louisa and Spotsylvania counties. The Valzinco lead-zinc mine and the Mitchell gold prospect are abandoned sites in Spotsylvania County. As a result of environmental impacts associated with historic mining, both sites were prioritized for reclamation under the Virginia Orphaned Land Program administered by the Virginia Department of Mines, Minerals, and Energy (VDMME).

This report summarizes geochemical data for all solid sample media, along with mineralogical data, and results of weathering experiments on Valzinco tailings and field experiments on sediment accumulation in Knights Branch. These data provide a framework for evaluating water-rock interactionsand geoenvironmental signatures of long-abandoned mines developed in massive sulfide deposits and low-sulfide gold-quartz vein deposits in the humid temperate ecosystem domain in the eastern United States.