New Mexico Geological Society Annual Spring Meeting — Abstracts

Most of our electronic equipment, such as smartphones, laptops, computer chips, wind turbines, hybrid and electric cars, etc., depend on rare earth elements (REE) and other critical minerals. This coupled with the anticipated rise in demand for critical minerals and the potential shortage of production capacity from China and other nations has made it necessary to examine New Mexico (NM) mine wastes for critical mineral and future mining potential. In the 274 mining districts in NM, including those for coal, uranium, metals, and industrial minerals, there are tens of thousands of inactive or abandoned mine features. These features range in depth from shallow prospect pits to 500-feet-deep mine shafts. To comprehend its composition, accurately estimate its volume, and determine its potential economic value, it is imperative to categorize these wastes. Hence this project seeks to: 1) characterize and estimate the critical mineral endowment of mine wastes in two mining districts in NM (i.e., Copper Flat at Hillsboro and Carlisle-Center mines in Steeple Rock district), 2) “beta-test” USGS procedures for sampling mine wastes. Future mining of mine wastes that potentially contain critical minerals can help pay for reclamation and clean up these sites. Critical mineral endowment of mine wastes in two mining districts in New Mexico (Copper Flat at Hillsboro and Carlisle-Center mines in the Steeple Rock district) were characterized and estimated. Potential critical minerals at these deposits include As, Bi, Te, Zn, Co, Ni, Mg, Mn, and fluorite. pH and particle size of samples were analyzed to determine weathering and migration potential of heavy metals. Soil pH was also measured to determine the potential for acid rock drainage for several mine waste. The S present in samples from Carlisle-Center mines are mostly acid forming and can potentially cause acid mine drainage that can dissolve other minerals. Samples from Copper Flat that are nonacid forming may be used as back fill material. Most of the waste rock pile at Copper Flat is characterized by a relatively coarse sand fraction. Difference in particle size fractions and the distribution along the slope are generally influenced by natural occurrences (e.g., gravity and pre-mining hydrothermal alteration) and operational activities such as material piling or dumping. Further studies includes analyses of geochemistry of different particle fractions to ascertain any existing correlation between mineralogy and particle size. Also, a bulk density test should be conducted to compute for the mass of mine waste piles and thus estimate the critical mineral endowment of the studied mine waste areas.