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Efficient and Accurate Identification of Platinum-Group Minerals by a Combination of Mineral Liberation and Electron Probe Microanalysis with a New Approach to the Offline Overlap Correction of Platinum-Group Element Concentrations*

Published online by Cambridge University Press:  21 July 2015

Inga Osbahr ,
Joachim Krause ,
Kai Bachmann  and
Jens Gutzmer
Inga Osbahr*
Affiliation:
Helmholtz Center Dresden—Rossendorf, Helmholtz-Institute Freiberg for Resource Technology, Halsbrücker Str. 34, D-09599 Freiberg, Germany
Joachim Krause
Affiliation:
Helmholtz Center Dresden—Rossendorf, Helmholtz-Institute Freiberg for Resource Technology, Halsbrücker Str. 34, D-09599 Freiberg, Germany
Kai Bachmann
Affiliation:
Helmholtz Center Dresden—Rossendorf, Helmholtz-Institute Freiberg for Resource Technology, Halsbrücker Str. 34, D-09599 Freiberg, Germany
Jens Gutzmer
Affiliation:
Helmholtz Center Dresden—Rossendorf, Helmholtz-Institute Freiberg for Resource Technology, Halsbrücker Str. 34, D-09599 Freiberg, Germany Department of Mineralogy, Technische Universität Bergakademie Freiberg, Brennhausgasse 14, D-09596 Freiberg, Germany
*
*Corresponding author.[email protected]
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Abstract

Identification and accurate characterization of platinum-group minerals (PGMs) is usually a very cumbersome procedure due to their small grain size (typically below 10 µm) and inconspicuous appearance under reflected light. A novel strategy for finding PGMs and quantifying their composition was developed. It combines a mineral liberation analyzer (MLA), a point logging system, and electron probe microanalysis (EPMA).

As a first step, the PGMs are identified using the MLA. Grains identified as PGMs are then marked and coordinates recorded and transferred to the EPMA. Case studies illustrate that the combination of MLA, point logging, and EPMA results in the identification of a significantly higher number of PGM grains than reflected light microscopy. Analysis of PGMs by EPMA requires considerable effort due to the often significant overlaps between the X-ray spectra of almost all platinum-group and associated elements. X-ray lines suitable for quantitative analysis need to be carefully selected. As peak overlaps cannot be avoided completely, an offline overlap correction based on weight proportions has been developed. Results obtained with the procedure proposed in this study attain acceptable totals and atomic proportions, indicating that the applied corrections are appropriate.

Keywords

mineral liberation analysiselectron probe microanalyzerplatinum-group elementsoverlap correctionoffline overlap factors
Type
EMAS Special Issue
Information
Microscopy and Microanalysis , Volume 21 , Supplement 5 , October 2015 , pp. 1080 - 1095
Copyright
© Microscopy Society of America 2015 

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Footnotes

*

This article is intended for the Special Issue from the EMAS 2014 Workshop on “Electron Probe Microanalysis of Materials Today – Rare and Noble Elements: from Ore Deposits to High-tech Materials”.

References

Åmli, R. & Griffin, W.L. (1975). Microprobe analysis of REE minerals using empirical correction factors. Am Mineral 60, 599–606.Google Scholar
Bence, A.E. & Albee, A.L. (1968). Empirical correction factors for the electron microanalysis of silicates and oxides. J Geology 76, 382–403.Google Scholar
Bolz, R.E. & Tuve, G.L. (1976). CRC Handbook of Tables of Applied Engineering Science. Cleveland, OH: CRC Press.Google Scholar
Cabri, L.J. (2002). The platinum-group minerals. In Geology, Geochemistry, Mineralogy and Mineral Beneficiation of Platinum-Group Elements, Cabri, L.J. (Ed.), pp. 13–129. Montreal, Quebec, Canada: Canadian Institute of Mining, Metallurgy and Petroleum. Special volume 54.Google Scholar
Cabri, L.J., Kojonen, K., Gervilla, K., Oberthür, T., Weiser, T., Johanson, B., Sie, S.H., Campbell, J.L., Teesdale, W.J. & Laflamme, J.H.G. (2002). Comparison of PGE trace analyses of pentlandite and some arsenides and sulfarsenides by EPMA and Micro-PIXE. 9th International Platinum Symposium, Program Abstracts, Billings, Montana, USA, pp. 73–76.Google Scholar
Fandrich, R., Gu, Y., Burrows, D. & Moeller, K. (2007). Modern SEM-based mineral liberation analysis. Int J Miner Process 84, 310–320.Google Scholar
Fialin, M. (1992). Background determination in wavelength-dispersive electron microprobe analysis: Some difficulties and presentation of a new analytical model. X-ray Spectrum 21, 175–181.Google Scholar
Fialin, M., Rémy, H., Richard, C. & Wagner, C. (1999). Trace element analysis with the electron microprobe: New data and perspectives. Am Mineral 84, 70–77.Google Scholar
Fleet, M.E. & Stone, W.E. (1990). Partitioning of platinum-group elements in the Fe-Ni-S system and their fractionation in nature. Geochim Cosmochim Acta 55, 245–253.Google Scholar
Gervilla, F., Cabri, L.J., Kojonen, K., Oberthür, T., Weiser, T.W., Johanson, B., Soey, H.S., Campbell, J.L., Teesdale, W.J. & Gilles Laflamme, J.H. (2004). Platinum-group element distribution in some ore deposits: Results of EPMA and micro-PIXE analyses. Microchimica Acta 147, 167–173.Google Scholar
Gregory, M.J., Lang, J.R., Gilbert, S. & Hoal, K.O. (2013). Geometallurgy of the pebble porphyry copper-gold-molybdenum deposit, Alaska: Implications for gold distribution and paragenesis. Econ Geol 108, 463–482.Google Scholar
Gu, Y. (2003). Automated scanning electron microprobe based mineral liberation analysis. An introduction to JKMRC/FEI mineral liberation analyser. J Miner Mater Characterization Eng 2, 33–41.Google Scholar
Haggerty, S.E. (1983). The mineral chemistry of new titanates from the Jagersfontein kimberkite, South Africa: Implications for metasomatism in the upper mantle. Geochim Cosmochim Acta 47, 1833–1854.CrossRefGoogle Scholar
Heinrich, K.F.J. & Newbury, D.E. (1991). Electron Probe Quantitation. New York, NY: Plenum Press.CrossRefGoogle Scholar
Jones, M.P. (1987). Applied Mineralogy: A Quantitative Approach. Norwell, MA: Graham & Trotman, London.Google Scholar
King, R.P. (1993). Basic image analysis for mineralogy. In International Congress of applied mineralogy 1993, Demonstration Workshop Manual. Griffin, B. Graham, J. & Linge, H. (Eds.), pp. 110–139. Perth, Australia: Demonstration Workshop Manual.Google Scholar
Krause, J., Brügman, G.E. & Pushkarev, E.V. (2005). Os-isotopes and PGE geochemistry of mafic-ultramafic Uralian-Alaskan type complexes in the Urals, Russia. In Extended Abstracts, 10th International Platinum Symposiu m , Törmänen, T.O. & Alapieti, T.T. (Eds.), pp. 437–440. Oulu, Finland: Geological survey of finland.Google Scholar
Krause, J., Brügmann, G.E. & Pushkarev, E.V. (2007). Accessory and rock forming minerals monitoring the evolution of zoned mafic-ultramafic complexes in the Central Ural Mountains. Lithos 95, 19–42.Google Scholar
O´Driscoll, B., Butcher, A.R. & Latypoc, R. (2014). New insights into precious metal enrichment on the Isle of Rum, Scotland. Geol Today 30, 134–141.CrossRefGoogle Scholar
Osbahr, I., Klemd, R., Oberthür, T., Brätz, H. & Schouwstra, R. (2013). Platinum-group element distribution in base-metal sulphides of the Merensky Reef from the eastern and western Bushveld Complex, South Africa. Minerlaium Deposita 48, 211–232.Google Scholar
Osbahr, I., Oberthür, T., Klemd, R. & Josties, A. (2014). Platinum-group element distribution in base-metal sulphides of the UG2 chromitite, Bushveld Complex, South Africa—A reconnaissance study. Mineralium Deposita 48, 211–232.Google Scholar
Petruk, W. (2000). Applied Mineralogy in the Mining Industry. Amsterdam: Elsevier Science BV.Google Scholar
Philibert, J. (1963). X-ray optics and x-ray microanalysis. In Proceedings of the Third International Symposium, Stanford University, Pattee H.H., Cosslett, V.E. & Engström, A. (Eds.), p. 379. New York, NY: Academic Press.Google Scholar
Philibert, J. & Tixier, R. (1968). Electron penetration and the atomic number correction in electron probe microanalysis. J Phys 1, 685–694.Google Scholar
Pouchou, L. & Pichoir, F. (1984). A new model for quantitative X-ray microanalysis. Reserche Aerospatiale 3, 167–192.Google Scholar
Pyle, J.M., Spear, F.S. & Wark, D.A. (2002). Electron microprobe analysis of REE in apatite, monazite and xenotime: Protocols and pitfalls. In Reviews in Mineralogy and Geochemistry, Volume 48: Phosphates, Kohn, M.L., Rakovan, J. & Hughes, J.M. (Eds.), pp. 337–362. Washington, DC: Mineralogical Society of America.Google Scholar
Reed, S.J.B. (1965). Characteristic fluorescence corrections in electron probe microanalysis. Br J Appl Phys 16, 913–926.Google Scholar
Roeder, P.L. (1985). Electron-microprobe analysis of minerals for rare-earth elements: Use of calculated peak-overlap corrections. Can Mineral 23, 263–271.Google Scholar
Sandmann, D. & Gutzmer, J. (2014). Nature and distribution of PGE mineralization in gabbroic rocks of the Lusatian Block, Saxony, Germany. German J Geosci 166, 35–53.Google Scholar
Segalstad, T.V. & Larsen, A.O. (1978). Gadolinite-(Ce) from Skien, southwestern Oslo region, Norway. Am Mineral 63, 188–195.Google Scholar
Tolstykh, N., Kozlov, A. & Telegin, Y. (2015). Platinum mineralization of the Svetley Bor and Nizhny Tagil intrusions, Ural Platinum Belt. Ore Geol Rev 67, 234–243.Google Scholar
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