2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 296-17
Presentation Time: 1:00 PM

CHEMICAL AND MINEROLOGICAL CHARACTERIZATION OF ABANDOND MINE WASTE IN NORTHEASTERN ARIZONA


ALI, Abdul-Mehdi S.1, AVASARALA, Sumant2, BREARLEY, Adrian3, CERRATO, Jose2 and BLAKE, Johanna M.T.4, (1)Department of Earth and Planetary Sciences, The University of New Mexico, Albuquerque, NM 87131-0001, (2)Civil Engineering, The University of New Mexico, Albuquerque, 87131, (3)Earth and Planetary Sciences, University of New Mexico, MSC03 2040, Albuquerque, NM 87131, (4)Chemistry, University of New Mexico, Albuquerque, NM 87131, mehdiali@unm.edu

Advanced microscopy, spectroscopy, and aqueous chemical extractions were integrated to investigate heavy metal contamination at the Blue Gap Tachee Claim 28 abandoned mine waste site of the Navajo nation in northeastern Arizona. Inductively coupled plasma optical emission spectroscopy (ICP-OES) measurements of chemical acid extractions performed on samples collected at this site confirmed the presence of V (4890 mg/kg), As (19.6 mg/kg) and U (1514 mg/kg). X-ray fluorescence spectroscopy (XRF) results revealed the presence of S (223 mg/kg). The XPS analyses conducted on these samples indicate the predominance of Fe(II) [73%], Fe(III) [27%], U(VI), V(V), and As(0), which is an uncommon oxidation state of arsenic in the environment. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and transmission electron microscopy (TEM) analyses detected the presence of carnotite (K2(UO2)2V2O8). We hypothesize that arsenopyrite (FeAsS) is present due to the coexistence of Fe, S, and As in these samples. Understanding secondary speciation in abandoned mine wastes is important to determine the fate and transport of heavy metals, and assess the risks posed to communities that live in close proximity to these sites.