MINERALOGICAL INVESTIGATIONS OF BLACK SHALE AND SIDERITE OF THE GRUNDY FORMATION IN NORTHERN BREATHITT COUNTY, KENTUCKY: ENVIRONMENTAL CONCERNS

Black shale is well known as a very important energy resource for natural gas and oil extraction and production. While extensive research has been done on the environmental concerns associated with oil and natural gas extraction, there has been less extensive research done on the natural environmental effects of black shale itself, particularly in the context of metal pollution. Black shales play a very important role in the environment as it acts as a major geologic control on the quality of the environment where they occur. Surface samples of black shales and associated siderite beds of the Grundy Formation from northern Breathitt County, Kentucky have never before been analyzed using detailed mineralogical techniques for environmental metal assessment. Such studies are warranted in the future due to recent trace amounts of silver being found in the area. Whether the silver or other precious metals occur in the shales that are of any economic value is unknown at this time. Associated with the shale are thin beds of siderite that research has proven to contain many precious metals. Powder X-ray diffraction indicates illite and ripidolite as being the dominant clay minerals present within the shale samples. Preliminary SEM results indicate the presence of galena, pyrite, chalcopyrite, and silver occur in minor quantities in some of the siderite beds. Weathering of the Grundy shales poses an environmental concern owing to Pb, Cu and Ag content of these minerals. Forestry, mining and road construction activities have further exposed the shales and have likely resulted in an increase of rates of weathering process of the shales. Detailed studies of bulk chemistry for the purpose of environmental and economic resource evaluation are clearly warranted in Breathitt County, Kentucky which suffers from numerous socioeconomic problems. This study forms a basis for broader regional environmental and economic concerns.