Paper No. 8
Presentation Time: 3:40 PM
UNUSUAL MINERALOGY (TRACE SILVER AND MAGNETITE) AND GEOCHEMISTRY OF STREAM SEDIMENTS FROM A PROPERTY WITH 200 YEARS OF MIXED USE IN NORTHERN BREATHITT COUNTY, KENTUCKY
The Wyatt property in northern Breathitt County, eastern Kentucky is 750 acres and is privately owned and has a long history of varied land use, which includes farming, natural gas wells, forestry, and coal mining. Bedrock on the property consists of Pennsylvanian Breathitt Group sandstones. Family history indicates metals or minerals of value may have been found on the property in the 1870s to 1880’s. Twenty nine sediment samples from various locations around the property, including stream beds, hillsides, and a floodplain were collected to test for the presence of any unusual or economic minerals. Analysis of these sediments indicate they are dominated by quartz however lithic fragments dominated by magnetite have been observed and sediment samples with percentages as high as 5% magnetite have been found. Scanning electron microscopy (SEM) indicates that many smaller silver flakes occur in samples and one example of a 100 micrometer diameter silver flake was found. However, inductively coupled plasma – optical emission spectroscopy (ICP-OES) analyses of bulk sediment indicate silver occurs in concentrations of only 0.5 to 1.7 ppm (bulk crustal abundance is 0.075 ppm). There is a positive correlation between bulk zirconium and silver concentrations with an r2 value of 0.58 suggesting a sedimentary concentration effect. Preliminary analysis indicates that the silver is geologic in origin and not a result of environmental pollution; however the levels of silver are not economic. Nickel concentrations are observed and vary from approximately 20 - 50 ppm and have weak correlation with the silver. SEM work found several examples of Nd-rich minerals (commonly 11 to 22 wt% by EDS) in a single sample, however bulk ICP-OES data indicate bulk neodymium concentrations are approximately 30-50 ppm. Cerium vs neodymium shows a strong correlation with an r2 value of 0.95 and suggests a single sediment source. Trends in trace elements (strontium, barium, scandium, and rubidium) also suggest a single sediment source with a strong correlations between strontium and barium (r2 = 0.92) and scandium vs rubidium (r2 = 0.86). Results indicate that surface sediment is more mineralogically diverse than expected and such surveys may play a role in mineral exploration in the Appalachians.