New Mexico Geological Society Annual Spring Meeting — Abstracts

Although, the physical safety-hazard of some inactive uranium mines in New Mexico have been mitigated, there still remain other uranium mines that have not been reclaimed. This project characterize samples from waste rock piles in the Lucky Don and Little Davie mines, Chupadero mining district, and Jeter mine, Ladron Mountains (all in Socorro County, NM) as to their mineralogical and geochemical composition, possible release of trace elements into the into the environment, their acid/neutralizing potential, and their stability as a result of erosion and weathering. The waste rock piles consist of heterogeneous mixtures of low-grade ore and waste rock. Mines in the study area have been mined either by surface and/or underground methods from pits, shafts and/or adits, and waste rock piles are located around or near the openings of these features. Waste rock piles at each mine site were sampled in a specific grid pattern tailoring to the size of that particular waste rock pile. Approximately 20-30 discrete samples were combined to form a single composite waste rock sample. This grid pattern sampling method was used in order to maximize surface area coverage, ensuring statistically representative sampling, and to obtain homogenized samples of the waste rock pile in a single sample. Although no evidence of potential acid drainage was observed from waste rock piles in the study areas, field scintillometer mapping indicated elevated radioactivity from some waste rock piles. Analytical techniques employed to answer questions regarding characterization include paste pH and paste conductivity, XRD analyses, electron microprobe analyses and whole-rock geochemical analyses for major and trace elements. Paste pH results from waste rock piles were greater than 5.5 (7-9) indicating a nonacid generating environment. XRD and electron microprobe analyses identified uranium and vanadium minerals in most of the waste rock piles. ICP-MS analyses indicated elevated (>100 ppm) values of uranium and vanadium in most of the waste rock piles.