Environmental processes that affect mineral deposits in the eastern United States

Abstract

A thorough understanding of the environmental processes that affect mineral deposits and mine wastes has become increasingly important as the Nation wrestles with how to meet our current demand for metals without compromising the environment and how to mitigate the damage caused by the mining practices of previous generations. Regulatory requirements are dominated by empirical approaches to environmental problems associated with mining, but mitigation and reclamation can be enhanced greatly by a theoretical and conceptual understanding of the processes that affect the availability, transport, and fixation of metals and the generation of acidic waters. U.S. Geological Survey (USGS) research efforts in the Eastern United States are concentrating on environmental processes that affect a class of mineral deposits known as massive sulfide deposits. These occurrences were valued historically for their sulfur content and recently for their metals. This deposit type is a research priority because of its economic significance and high potential for adverse environmental impact due to its high sulfide content and the low acid-buffering capacity of host rocks. Numerous examples of these deposits are found in the East, including reclaimed mine sites, abandoned mines, active mines, and sites currently in the permitting process for future production. Published studies of mine drainage chemistry from the Iron Mountain massive sulfide deposit in California have documented extreme conditions of very low pH and high heavy-metal concentrations. These extreme conditions are attributed to the unique hydrologic and climatic settings of the deposit and probably are independent of the mineral deposit type. Areas currently under study include Bald Mountain, Maine, the Great Smoky Mountains National Park, the Vermont copper belt, Contrary Creek, Virginia, and Prince William Forest Park, Virginia (fig.1). Goals of the research are (1) to give land-use planners and the mining industry a better empirical framework from which to assess potential environmental impacts of mining, particularly under eastern climatic conditions, and (2) to provide a better theoretical and conceptual framework from which to design more effective and cost efficient mitigation and reclamation programs.