New Mexico Geological Society Annual Spring Meeting — Abstracts

The growing demand for critical minerals and rare earth elements creates concerns for national security as these minerals are essential for many products needed to sustain our way of life and their supply chain susceptible to disruptions. This has resulted in exploring secondary sources such as mine waste and tailings for critical minerals. These mine wastes also pose environmental challenges. Weathering and oxidation of sulfide minerals dissolve and mobilize metals into the environment. This study aims to examine the distribution and mobility of critical minerals by leaching mine wastes with deionized water, using humidity cells following ASTM D5744 -18 method. The areas under study are known for their historic mining activities leaving behind significant amounts of mine waste and tailings. Mine wastes in Eureka, Hillsboro, McGhee Peak and Steeple Rock districts of Southwestern New Mexico contain significant concentrations of critical minerals since they were historically mined for base and precious metals and not critical minerals. Study areas include porphyry copper, skarn, epithermal gold and carbonate replacement deposits. The methods used in this research include, sample collection and preparation, mineralogical analysis using x-ray diffraction (XRD), Raman spectroscopy, petrographic analysis, column test, paste pH and Fizz test. Geochemical analysis includes specific conductance, pH and alkalinity test, sulfate measurements, Ion chromatography (IC), inductively coupled plasma mass spectroscopy (ICP-MS) and optical emission spectroscopy (ICP-OES) was conducted to determine the metal concentration in the leachate samples. Whole-rock geochemistry and XRD analysis indicates elevated levels of Cu, Zn, As, Pb, and Ag in these mine wastes from four mining districts in New Mexico compared to average crustal abundance. Concentrations of Cu from whole rock geochemistry data show 3944 ppm, 2387 ppm in Steeple Rock samples and 546 ppm, 576.5 ppm from Hillsboro samples. Concentrations of As and Zn range from 1470 ppm to 2490 ppm and 8530 ppm to 10300 ppm respectively in Eureka samples. McGhee Peak shows enrichment of Pb and Zn (2880 ppm, 12600 ppm) and (7880 ppm ,14700 ppm) respectively. Key findings show that mine waste are enriched in LREE and metal mobility is controlled by acid-generating or acid-neutralization potential of the area.