New Mexico Geological Society Annual Spring Meeting — Abstracts

Critical minerals and the elements they contain are at the forefront of the transition to clean energy and technological advancement. As such, global demand for these commodities is at an all-time high. To help meet domestic demand in the US, there is a push to quantify critical minerals in the US in both active and inactive mining sites and districts. New Mexico has a long history with mining, and many of its districts, though currently inactive, at one time produced mineral commodities that may be associated with critical minerals. These historic districts range widely in age, and many were operating when metallurgical processing technologies were in their infancy and, as a result, contain substantial critical mineral resources in their tailings and waste rock. Microbial communities that have developed in the decades since might have contributed to metal mobilization, but also represent a resource for bioremediation or potential ‘green mining’ of these deposits in the future. After extensive method development, we have begun characterizing the microbial communities inhabiting these waste rock piles using modern molecular microbiological techniques, and will present new data about the composition and abundance of microorganisms in historic mine waste. Preliminary data analysis indicates that microbial communities more closely resemble local soil microbiomes than traditional acid rock drainage (ARD) or bioleaching microbial communities. This is particularly evident when comparing the microbial community composition and diversity of waste rock piles that were topped with a soil cover to those with no soil cover. However, rare sulfur- and metal-oxidizing populations exist, and the waste rock piles contain abundant undescribed microorganisms with unknown metabolic capabilities. Our preliminary results show that there is a correlation between microbial communities and mine waste type, and we will continue to explore how waste geochemistry controls microbial diversity and the occurrence specific microbial populations.