Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-26T08:02:08.811Z Has data issue: false hasContentIssue false
  • English
  • Français

Characteristics of ore minerals associated with gold at the Prestea mine, Ghana

Published online by Cambridge University Press:  05 July 2018

Napoleon Q. Hammond  and
Hirokazu Tabata
Napoleon Q. Hammond
Affiliation:
Geological Institute, University of Tokyo, 7-3-1 Hongo, Tokyo 113, Japan
Hirokazu Tabata
Affiliation:
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152, Japan
Get access Rights & Permissions [Opens in a new window]

Abstract

Gold in Early Proterozoic Birimian greenstone at Prestea in Ghana is associated with base metal sulphides and sulphosalts including arsenopyrite, pyrite, sphalerite, chalcopyrite, pyrrhotite, galena, tetrahedrite, bournonite, boulangerite and jamesonite. The occurrence of the gold is intimately associated with arsenopyrite and the sulphosalts, and to a lesser extent with the other sulphides. The tetrahedrites at Prestea constitute the major component of sulphosalts associated with gold and occurring in two distinct types. Type I show ideal stoichiometric composition. Type II tetrahedrites deviated from the ideal stoichiometry and are represented approximately by the average formula (Cu,Ag)9.61(Fe,Zn)2.39(Sb,As)4S13. The tetrahedrites co-precipitated with gold exhibit ideal characteristics indicating an equilibruim state of the mineralizing fluid during precipitation. Three types of pyrites were distinguished by electron-microprobe analyses based on their As, Co and Ni composition. The As content in type I vary from 0.15 to 0.37 wt%, and contain up to 2 wt.% Co.Type II pyrites are As-rich and form the most dominant with As content ranging from 0.2 to 2.69 wt.%. Ni content varies from below-detection to 1000 ppm. Type III pyrites are poor in the trace elements and consistent with the stoichiometric composition. The mineralization occurred in three paragenetic stages from at least a two-phase hydrothermal fluid, with stage II forming a prolonged and main stage of the ore and gold mineralization. Redox changes in ore fluid which were triggered by episodic pressure releases during fissuring and fracturing caused fluctuation of the activity of the As/Ni ratio and subsequent oscillatory zoning of Ni in As-rich ores.

Keywords

ore mineralsgoldgreenstonePresteaGhana
Type
Mineralogy
Information
Mineralogical Magazine , Volume 61 , Issue 409 , December 1997 , pp. 879 - 894
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arehart, G.B., Chyrssoulis, S.L. and Kesler, S.E. (1993) Gold and arsenic in iron sulphides from sediment-hosted disseminated gold deposits: Implications for depositional processes. Econ. Geol., 88, 171—85.CrossRefGoogle Scholar
Ballantyne, J.M. and Moore, J.N. (1988) Arsenic geochemistry in geothermal systems. Geochim. Cosmochim. Acta, 52, 475-83.CrossRefGoogle Scholar
Black, R. (1980) Precambrian of West Africa. Episodes, 4, 3–8.CrossRefGoogle Scholar
Bowell, R.J. (1992) Supergene gold mineralogy at the Ashanti, Ghana: Implications for the supergene behaviour of gold. Mineral. Mag., 56, 545—60.CrossRefGoogle Scholar
Davies, D.W., Hirds, W., Schaltegger, U. and Nunoo, E.A. (1994) U-Pb age constraints on deposition and the provenance of Birimian and gold-bearing Tarkwain sediments in Ghana, West Africa. Precamb. Res., 67, 89-107.CrossRefGoogle Scholar
Dill, H.G., Weiser, T., Bernhardt, I.R. and Kilibarda, R.C. (1995) The composite gold-antimony vein gold deposit at Kharma (Bolivia). Econ. Geol., 90, 51-66.CrossRefGoogle Scholar
Eisenlohr, B.N. (1992) Conflicting evidence on the timing of mesothermal and palaeoplacer gold mineralization in early Proterozoic rocks from southwestern Ghana, West Africa. Mineral. Deposita., 27, 23-9.CrossRefGoogle Scholar
Eisenlohr, B.N. and Hirdes, W. (1992) The structural development of the early Proterozoic Birimian and Tarkwaian rocks of southwestern Ghana, West Africa. J. African Earth Sci., 14, 313-25.CrossRefGoogle Scholar
Fleet, M.E., MacLean, P.J. and Barbier, J. (1989) Oscillatory-zoned As-bearing pyrites from strata-bound gold deposits: An indication of the fluid evolution. Econ. Geol. Mon., 6, 356—362.Google Scholar
Hackbarth, C.J. and Petersen, U. (1984) A fractional crystallization model for the deposition of argentian tetrahedrite. Econ. Geol., 79, 448-60.CrossRefGoogle Scholar
Hammond, N.Q., and Shimazaki, H. (1994) Geology and geochemical aspects of ore formation at the Prestea mesothermal vein gold deposit in the Birimian system of Ghana. Internat. Geol. Review, 36, 715-31.CrossRefGoogle Scholar
Hawley, J.E. and Nichol, I. (1961) Selenium in some Canadians sulfides. Econ. Geol., 54, 467-87.CrossRefGoogle Scholar
Hirdes, W., Davis, D.W. and Eisenlohr, B.N. (1992) Reassessment of Proterozoic granitoid ages in Ghana on the basis of U/Pb zircon and monazite dating. Precamb. Res., 56, 89-96.CrossRefGoogle Scholar
Hutchison, M.N. and Scott, D.S. (1981) Sphalerite geobarometry in the Cu-Fe-Zn-S system. Econ. Geol., 76, 143-53.CrossRefGoogle Scholar
Johnson, N.E., Craig, J.R. and Rimstidt, J.D. (1986) Compositional trends in tetrahedrite. Canad. Mineral., 24, 385-97.Google Scholar
Kesse, G.O. (1985) The Mineral and Rock Resources of Ghana. Balkema, Rotterdam, 610pp.Google Scholar
Leube, A., Hirdes, W., Mauer, R. and Kesse, G.O. (1990) The early Proterozoic Birimian Supergroup of Ghana and some aspects of its associated gold mineralization. Precamb. Res., 46, 139—65.CrossRefGoogle Scholar
Lynch, J.V.G (1989) Large-scale hydrothermal zoning reflected in the tetrahedrite-freibergite solid solution, Keno Hill Ag-Pb-Zn district, Yukon. Canad. Mineral., 27, 383-400.Google Scholar
Miller, W.J. and Craig, J.R (1983) Tetrahedrite-tennantite series compositional variations in the Cofer deposit, Mineral district, Virginia. Amer. Mineral., 68, 227-34.Google Scholar
Mucke, A. and Dzigbodi-Adjimah, (1994) Ore textures and parageneses of the Prestea and Obuasi gold deposit in the Ashanti Belt of Ghana: An ore microscopy study. In Metallogenesis of Selected Gold Deposits in Africa (Oberthur, T., ed,). Geologisches Jahrbuch Reihe, 100, 167-99.Google Scholar
Mumin, A.H., Fleet, M.E. and Chryssoulis, S.L. (1994) Gold mineralization in As-rich mesothermal gold ores of the Bogosu-Prestea mining district of the Ashanti gold belt, Ghana: remobilization of ‘invisible’ gold. Mineral. Deposita, 29, 445—60.CrossRefGoogle Scholar
Ntiamoah-Agyakwa, Y. (1979) Relationship between gold and manganese mineralization in the Birimian of Ghana, West Africa. Geol. Mag., 116, 345-52.CrossRefGoogle Scholar
O'Leary, M.J. and Sack, R.O. (1987) Fe-Zn exchange reaction between tetrahedrite and sphalerite in natural environments. Contrib. Mineral. Petrol., 96, 415-25.CrossRefGoogle Scholar
Oberthur, T., Vetter, U., Mumm, A.S., Weiser, T., Amanor, J.A., Gyapong, W., Kumi, R. and Blenkinsop, T.G. (1994) The Ashanti gold deposit at Obuasi: Mineralogical, geochemical, stable iso-tope and fluid inclusion studies on the metallogen-esis of the deposit. In Metallogenesis of Selected Gold Deposits in Africa (Oberthur, T., ed.). Geologisches dahrbuch Reihe, 100, 31-131.Google Scholar
Rytuba, J. (1985) Geochemistry of hydrothermal transport and deposition of gold and sulfide minerals in Carlin-type gold deposit. U.S. Geol. Surv. Bull., 1646, 27-34.Google Scholar
Sack, R.O. and Loucks, R.R. (1985) Thermodynamic properties of tetrahedrite-tennantites: constraints on the interdependence of Ag-Cu, Fe-Zn, Cu-Fe, and As—Sb exchange reactions. Amer. Mineral., 70, 1270-89.Google Scholar
Sibson, R.H., Robert, F. and Poulsen, K.H. (1988) High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits. Geology, 16, 551-5.2.3.CO;2>CrossRefGoogle Scholar
Slim-shimi, N., Moëlo, Y., Tlig, S. and Lévy, C. (1996) Sulfide geochemistry and genesis of Chouichia and Ainel Bey copper deposits in northwestern Tunisia. Mineral. Deposita, 31, 188-200.CrossRefGoogle Scholar
Taylor, P.N., Moorbath, S., Leube, A. and Hirdes, W. (1992) Early Proterozoic crustal evolution in the Birimian of Ghana, Constraints from geochronology and isotope geochemistry. Precamb. Res., 56, 97-111.CrossRefGoogle Scholar
Wu, I. and Petersen, U. (1977) Geochemistry of tetrahedrite and mineral zoning at Casapalca, Peru. Econ. Geol., 72, 993–1016.CrossRefGoogle Scholar
Yardley, B.W.D., Rochelle, C.A., Barnicoat, A.C. and Lloyd, G.E. (1991) Oscillatory zoning in meta-metasomatism. Mineral. Mag., 55, 357—65.CrossRefGoogle Scholar