GSA Connects 2021 in Portland, Oregon

Paper No. 219-7
Presentation Time: 9:00 AM-1:00 PM


REWIS, John, GOODELL, Philip, ARRIBAS, Antonio, KUBICKI, James, PINGITORE, Nicholas and ENGLE, Mark, Department of Earth, Environmental and Resource Sciences, University of Texas at El Paso, 500 W University Ave, El Paso, TX 79968-8900

Due to a lack in exploitation for REEs deposits, much of the globe has experienced critical shortages of the precious metals. The Rio Grande Rift in west Texas has allowed for the resurgence of late stage magmatism along the rift shoulders to act as a conduit for REEs within fluorine rich hydrothermal fluids to gather in exploitable quantities. Fluorspar deposits along the rift occur either as a structurally controlled fissure veins or as replacement bedding in carbonate rocks. There have been over 100 potential fluorspar targets that occur in either laccoliths or within caldera environments along the Rio Grande Rift. Known concentrations of exploitable HREEs exist where fluorspar is present in Sierra Blanca, TX.

Reassessments are required towards the importance of former fluorspar mines and prospects along the Rio Grande Rift for its potential in an economically viable mineral deposit. Sampling of those former sites can produce trace element associations with REEs and other critical minerals. Trace element lithogeochemistry will be performed on the samples collected from potential targets.

Three target areas have been identified in Hudspeth County: Eagle Mountains, Sierra Blanca, and the Quitman Mountains. An estimated potential fluorspar reserve of 1,000,000 tons containing concentrations greater than 35% CaF2 is located within the Eagle Mountains, TX. In Sierra Blanca, TX previous exploration studies have identified HREE enrichment along with concentrations of beryllium and uranium. Total reserves of HREEs have been estimated to contain greater than 18,000 tons. Following the rift south into Brewster County, a high grade fluorspar deposit containing up to 50% CaF2 is located in the Christmas Mountains where large scale production of fluorspar has occurred in the past.. Further analysis is needed to determine its potential for REE mineralization.

Much of the chemical analysis done in this area is missing crucial REE data due to the lack of previous exploration. Potential results of this research can help explain how REE enrichment is related to rift shoulder magmatism. The crystal chemistry of fluorite is intended to serve as exploration tool for its ability to accommodate variable chemistry in similar tectonic environments.