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Mapping arsenopyrite alteration in a quartz vein-hosted gold deposit using microbeam analytical techniques

Published online by Cambridge University Press:  02 January 2018

M. Gilligan ,
A. Costanzo ,
M. Feely ,
G. K. Rollinson ,
E. Timmins ,
T. Henry  and
L. Morrison
M. Gilligan
Affiliation:
Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Galway, Ireland
A. Costanzo*
Affiliation:
Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Galway, Ireland
M. Feely
Affiliation:
Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Galway, Ireland
G. K. Rollinson
Affiliation:
Camborne School of Mines, School of Engineering, Mathematics and Physical Sciences, University of Exeter, Cornwall Campus, Penryn Cornwall TR10 9FE, UK
E. Timmins
Affiliation:
National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland
T. Henry
Affiliation:
Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Galway, Ireland
L. Morrison
Affiliation:
Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Galway, Ireland Ryan Institute, National University of Ireland, Galway, Ireland
*
E-mail: [email protected]
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Abstract

An unworked quartz vein-hosted gold deposit occurs in the Clew bay area of County Mayo, western Ireland. The veins are late-Caledonian in age and transect greenschist-facies poly-deformed Silurian quartzites. The veins contain disseminated arsenopyrite that may be a primary mineral source for elevated levels of arsenic (As) found in groundwater samples recovered from wells related spatially to the gold deposit. Levels from 5 to 188 μg/L (significantly above the 7.5 μg/L threshold for safe drinking water) have been detected. A series of element distribution maps using a scanning electron microscope (Hitachi model S-4700) linked to an energy-dispersive spectrometer (INCA® Oxford Instruments) and mineral distribution maps generated by QEMSCAN® (Quantitative Evaluation of Minerals by Scanning electron microscopy) were used to map the distribution of the primary arsenopyrite and related secondary As-bearing phases. Laser Raman microspectroscopy was used to identify the secondary As-bearing phases. 'Island weathering' of primary arsenopyrite together with hydrated pseudomorphs of arseniosiderite, pharmacosiderite and scorodite after arsenopyrite are recorded. Circulating groundwater hydrates the primary arsenopyrite, providing the release mechanism that forms the secondary As-bearing phases that occur as microfracture infills together with muscovite and biotite. The textural relationships between the primary and secondary As minerals indicate their potential as mineral sources of As that could enter transport pathways leading to its release into groundwater.

Keywords

arsenopyritegold depositCroagh Patrick
Type
Research Article
Information
Mineralogical Magazine , Volume 80 , Issue 5 , August 2016 , pp. 739 - 748
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2016

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References

Aherne, S., Reynolds, N.A. and Burke, D. (1992) Gold mineralization in the Silurian and Ordovician of South Mayo. Pp. 39-49 in: The Irish Minerals Industry 1980–1990.(A.A. Bowden, editor). Irish Association for Economic Geology, Dublin.Google Scholar
Basu, A. and Schreiber, M.E. (2013) Arsenic release from arsenopyrite weathering: Insights from sequential extraction and microscopic studies. Journal of Hazardous Materials, 262, 896–904.CrossRefGoogle ScholarPubMed
Bossy, A., Grosbois, C., Beauchemin, S., Courtin-Nomade, A., Hendershot, W and Bril, H. (2010) Alteration of As-bearing phases in a small watershed located on a high grade arsenic-geochemical anomaly (French Massif Central). Applied Geochemistry, 25, 1889–1901.CrossRefGoogle Scholar
Das, S. and Hendry, M.J. (2011) Application of Raman spectroscopy to identify iron minerals commonly found in mine wastes. Chemical Geology, 290, 101–108.CrossRefGoogle Scholar
Deer, W.A., Howie, R.A. and Zussman, J. (2013) An Introduction to the Rock-forming Minerals. 3redition. Mineralogical Society of Great Britain and Ireland, London, 498 pp.CrossRefGoogle Scholar
Drahota, P. and Filippi, M. (2009) Secondary arsenic minerals in the environment: A review. Environment International, 35, 1243–1255.CrossRefGoogle ScholarPubMed
European Communities Environmental Objectives (Groundwater) Regulations (2010) Statutory Instruments (SI) No 9 of 2010. Government of Ireland.Google Scholar
Filippi, M., Machovic, V., Drahota, P. and Bohmova, Y (2009) Raman microspectroscopy as a valuable additional method to X-ray diffraction and electron microscope/microprobe analysis in the study of iron arsenates in environmental samples. Applied Spectroscopy, 63, 621–626.CrossRefGoogle Scholar
Flora, S.J.S.. (2015) Arsenic: chemistry, occurrence, and exposure. Chapter 1 in: Handbook of Arsenic Toxicology(S.J.S. Flora, editor). Elsevier, 723 pp.Google Scholar
Foley, N.K. and Ayuso, R.A. (2008) Mineral sources and transport pathways for arsenic release in a coastal watershed, USA. Geochemistry: Exploration, Environment, Analysis, 8, 59—75.Google Scholar
Gilligan, M., Feely, M., Higgins, T., Henry, T., Zhang, C. and Morrison, L. (2010) Elevated arsenic in grounwater from the western Irish Caledonides: evidence for cross atlantic correlations with high arsenic groundwater provenances along the Appalachian-Caledonian belt. SEGH, Conference Schedule and Abstracts, p 56 [Available from www. nuigalway.ie/segh2010/download/SEGH2010% 20Book_of_Abstracts.pdf].Google Scholar
Gilligan, M., Feely, M., Henry, T., Higgins, T., Zhang, C., Timmins, E., Rollinson, G.K. and Morrison, L. (2013) Spatial distribution of As in gold bearing quartz veins from a high As groundwater region in the Caledonides of Western Ireland.GSA Abstracts with programs, 45, No. 1, p. 46 [Available from https://gsa.confex.com/ gsa/2013NE/webprogram/Paper216124.html].Google Scholar
Gomez, M.A., Becze, L., Blyth, R.I.R.., Cutler, J.N. and Demopoulos, G.P. (2010) Molecular and structural investigation of yukonite (synthetic & natural) and its relation to arseniosiderite. Geochimica et Cosmochimica Acta, 74, 5835–5851.CrossRefGoogle Scholar
Goodall, W.R., Scales, P.J. and Butcher, A.R. (2005) The use of QEMSCAN and diagnostic leaching in the characterization of visible gold in complex ores. Minerals Engineering, 18, 877—886.Google Scholar
Gottlieb, P., Wilkie, G., Sutherland, D., Ho—Tun, E., Suthers, S., Perera, K., Jenkins, B., Spencer, S., Butcher, A. and Rayner, I (2000) Using quantitative electron microscopy for process mineralogy applications. Journal of the Minerals Metals & Materials Society, 52, 24–25.CrossRefGoogle Scholar
Henry, T. (2014)An integrated approach to characterising the hydrogeology of the Tynagh Mine catchment, County Galway, Ireland. Unpublished PhD Thesis, National University of Ireland Galway, Ireland [http:// hdl.handle.net/10379/3976].Google Scholar
Hinkle, S.R. and Polette, D.J. (1999) Arsenic in Ground Water of the Willamette Basin, Oregon. Department of the Interior U.S. Geological Survey. Water-Resources Investigations Report 98—4205.Google Scholar
Johnston, J.D. and McCaffrey, K.J.W.. (1996) Fractal geometries of vein systems and the variation of scaling relationships with mechanism. Journal of Structural Geology, 18, 349–358.CrossRefGoogle Scholar
Knappett, C., Pirrie, D., Power, M.R., Nikolakopoulou, I., Hilditch, J. and Rollinson, G.K. (2011) Mineralogical analysis and provenancing of ancient ceramics using automated SEM-EDS analysis (QEMSCAN®): a pilot study on LB I pottery from Akrotiri, Thera. Journal of Archaeological Science, 38, 219–232.CrossRefGoogle Scholar
Lipfert, G. (2006) A geochemical, isotopic andpetrologic study of a watershed with arsenic-enriched ground water in Northport, Maine. PhD Thesis, University of Maine, Orono, USA.Google Scholar
Mernagh, T.P. and Trudu, A.G. (1993) A laser Raman microprobe study of some geologically important sulphide minerals. Chemical Geology, 103, 113-127.CrossRefGoogle Scholar
Nesbitt, H.W., Muir, I.J. and Prarr, A.R. (1995) Oxidation of arsenopyrite by air and air-saturated, distilled water, and implications for mechanism of oxidation. Geochimica et Cosmochimica Acta, 59, 1773-1786.CrossRefGoogle Scholar
Pirrie, D. and Rollinson, G.K. (2011) Unlocking the applications of automated mineral analysis. Geology Today, 27, 235-244.CrossRefGoogle Scholar
Robertson, F.N. (1989) Arsenic in ground-water under oxidizing conditions, south-west United States. Environmental Geochemistry and Health, 11, 171-186.CrossRefGoogle Scholar
Smedley, P.L. and Kinniburgh, D.G. (2002) A review of the source, behaviour and distribution of arsenic in natural waters. Applied Geochemistry, 17, 517-568.CrossRefGoogle Scholar
Stumm, W. and Morgan J.J. (1996) Aquatic Chemistry, Chemical Equilibria and Rates in Natural Waters. 3rd edition. JohnWiley & Sons, Inc., New York, 1022 pp.Google Scholar
Wilkinson, J.J. and Johnston, J.D. (1996) Pressure fluctuations, phase separation, and gold precipitation during seismic fracture propagation. Geology, 24, 395-398.2.3.CO;2>CrossRefGoogle Scholar
Utsunomiya, S., Peters, S.C., Blum, J.D. and Ewing, R.C. (2003) Nanoscale mineralogy of arsenic in a region of New Hampshire with elevated As concentration in the groundwater. American Mineralogist, 88, 1844-1852.CrossRefGoogle Scholar