CRITICAL MINERAL POTENTIAL OF MISSISSIPPI VALLEY-TYPE MINERALIZATION IN KENTUCKY

Fluorite, sphalerite, galena, and barite occurrences are common in Kentucky, mainly concentrated in three distinct areas with historical production and exploration activities. In westernmost Kentucky, which is part of the Illinois-Kentucky Fluorspar District, mineralization is dominated by fluorite and includes important sphalerite occurrences. Minerals that form here are typically associated with ultramafic igneous intrusions. Contrary to the remarkably high rare earth element (REE) contents measured at Hicks Dome in southern Illinois, the REE contents in Kentucky are surprisingly low (negligible in fluorite, max. 620 ppm, avg. 335 ppm measured on igneous dikes). The highest measured germanium content in sphalerite in western Kentucky reached 1050 ppm. In southcentral Kentucky, mineralization is dominated by sphalerite, similarly to the neighboring Middle Tennessee Mines. Sampling is currently underway to determine the germanium content of the sphalerite in the southcentral Kentucky area. While mineral paragenesis in central Kentucky is similar to the other occurrences, this area stands out due to its historical barite production. An upcoming Earth MRI project will target the critical mineral assessment of this area. Our ongoing research, aided by the high-resolution airborne geophysics data collected by USGS, will shed light on the structural control and fluid evolution history that resulted in the varied Mississippi Valley-type mineralization in Kentucky and the associated critical mineral potential.