COMPARATIVE ANALYSIS OF LABORATORY AND PORTABLE X-RAY FLUORESCENCE METHODS FOR GALLINAS MOUNTAINS ROCK SAMPLES

The Energy Act of 2020 defined critical minerals as those that are essential to the economic and national security of the United States and serve an essential function in the manufacturing of products such as computers, smartphones, abrasives, and a host of other technologies. The critical minerals list of 2022 includes 50 elements, including the rare earth elements (REE). Over the last decade the New Mexico Bureau of Geology and Mineral Resources (NMBGMR) and the United States Geological Survey (USGS) have been reevaluating known mining districts in New Mexico to analyze the potential for critical minerals. The Gallinas Mountains, located in the Lincoln County porphyry belt, is one such mining district known to contain critical minerals such as REE, fluorite, and barite hosted within hydrothermal veins and breccias. The primary REE mineral in the district is bastnäsite [(REE)CO3F], the same ore mineral as significant global REE producers such as the Mountain Pass mine (California, USA) and Bayan Obo mine (Inner Mongolia, China). The highest REE values in grab samples to date from the Gallinas Mountains reach up to around 8% total REE. This study aims to assess the accuracy of portable X-ray fluorescence (PXRF) analysis (PXRF) to determine if it can be a reliable tool to analyze for critical minerals in the unusual rocks of the Gallinas Mountains. Samples of veins and altered host rocks from the Gallinas Mountains were previously sent to ALS Global for whole rock and trace element geochemical analysis. A comparison study will be conducted between the whole rock and trace element geochemical data and data collected with PXRF on the returned powdered samples. Initial results show that the PXRF can be reliable for measuring some critical minerals, however it does not detect elements lighter than phosphorus. The PXRF analyzer used in this study does not distinguish between the REE, and does not detect barium, making it of limited value in exploring for critical minerals in the Gallinas Mountains at this time.