A SYSTEMATIC ASSESSMENT OF POTENTIALLY TOXIC NATURALLY OCCURRING MINERALS

Disturbed Earth materials are potentially problematic in the environment; exposing previously buried metal-bearing minerals, such as arsenopyrite or galena, to atmospheric oxygen and surface fluids initiates weathering. Very often, weathering processes release toxic metals and other chemical compounds into soils and waterways. Uptake of mobilized toxic metals can weaken autonomic functions in both aquatic and terrestrial life. Much of what is known about the contaminant potential of metalliferous minerals has been learned after exposure, both atmospheric and biologic. A method, or system, that would provide beforehand knowledge of contaminant potential is currently being developed by the U.S. Geological Survey. The USGS minerals characterization method combines determinative mineralogy, geochemistry, and biochemistry to produce a comprehensive description of a given mineral – its crystalline and chemical composition; its leach propensity, buffering capacity, and acid-generating potential; its solubility and reactivity in fluids compositionally similar to human gastric and lung fluids; and its ecotoxicological affects. This store of information, acquired by standardized, reproducible procedures, may be used to anticipate, or predict, the behavior of exposed metalliferous minerals in as-yet undeveloped environments and human communities.