Geology and Geochemistry of the Sierra Blanca Rare Earth Complex, Sierra Blanca, Texas

With an increasing standard of living comes an increase in demand for high tech goods, environmentally friendly (green) and military technologies, and the inherent need to procure the necessary raw materials. Demand for the rare earth elements (REE) is on the rise, and there is no foreseeable decline in the need for accessible deposits. Between 2010 and present, the United States Congress has heard numerous reports on the importance of REE, and in 2012 the Department of Defense(DoD)declared REE a critical resource, with implications for national security. The Sierra Blanca laccoliths, 150 kilometers southeast of El Paso, TX represent a potential low grade/high tonnage deposit that is especially interesting due to the high heavy rare earth content. Previous work has suggested that the Sierra Blanca laccoliths offer a unique opportunity to explore and develop a domestic source of this critical resource Thorough geologic mapping of the laccoliths has allowed previously unmapped structures and contacts to be associated with geochemical data from whole rock and trace analyses of 70 rhyolite surface samples. Detailed information about the concentration, zoning, and dispersion of REE are incorporated into a characterization of the deposit, showing an enrichment of REE throughout the laccoliths, with late stage enrichment through the action of F-rich fluids evident at the contact and fracture zones. Yttrofluorite is the major REE bearing mineral, with minor amounts of xenotime and bastní¤site being found primarily on Round Top Mountain. The Sierra Blanca laccoliths represent a new REE deposit type, and with an understanding of the geology and geochemistry associated with the Sierra Blanca REE deposit, this research creates a basis for future exploration in the search for domestic sources of this critical resource