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Graftonite in phosphatic iron formations associated with the mid-Proterozoic Gamsberg Zn-Pb deposit, Namaqua Province, South Africa

Published online by Cambridge University Press:  05 July 2018

M. Stalder  and
A. Rozendaal
M. Stalder
Affiliation:
Department of Geology, University of Stellenbosch, Chamber of Mines Building, Private Bag X1, Stellenbosch 7600, South Africa
A. Rozendaal*
Affiliation:
Department of Geology, University of Stellenbosch, Chamber of Mines Building, Private Bag X1, Stellenbosch 7600, South Africa
*
*E-mail: [email protected]
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Abstract

Granular aggregates of fine-grained graftonite (Fe,Mn,Ca)3(PO4)2 and intergrown wolfeite (Fe,Mn)2(PO4)(OH) occur in amphibolite-facies metamorphosed iron formations associated with the Gamsberg Zn-Pb deposit, South Africa. To date, these minerals were believed to have limited parageneses, being essentially restricted to granitic pegmatites and iron meteorites. This paper is the first report of the occurrence of graftonite and wolfeite in a regionally metamorphosed, iron formation-hosted setting. The aggregates are found together with Mn- and Pb-rich apatite and calcian pyromorphite in a pristine unit of almost pure chemical precipitates, the origin of which is intimately linked to the base-metal mineralizing process. Evidence from Gamsberg supports previous studies conducted on pegmatite-hosted graftonites that a simple host rock mineralogy and geochemical prerequisites, such as high activities of Fe, Mn, Ca and a deficiency in F, exert a dominant control on the stabilization of these minerals. However, in a marine sedimentary environment, significant concentrations of phosphorus have to be precipitated to prevent stabilization of all the phosphorus as fluorapatite. The paucity of graftonite in such settings suggests that the combination of these requirements is only rarely achieved.

Keywords

graftonitewolfeiteiron formationsGamsberg Zn-Pb depositSouth Africa
Type
Research Article
Information
Mineralogical Magazine , Volume 66 , Issue 6 , December 2002 , pp. 915 - 927
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2002

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References

Ashley, P.M., Lottermoser, B.G. and Scott, K.M. (1997) Supergene iron phosphate minerals in Proterozoic ironstones from the Olary Block, South Australia. Neues Jahrbuch für Mineralogie Monatshefte, 309–327.CrossRefGoogle Scholar
Ashley, P.M., Lottermoser, B.G. and Westaway, J.M. (1998) Iron-formations and epigenetic ironstones in the Palaeoproterozoic Willyama Supergroup, Olary Domain, South Australia. Mineralogy and Petrology, 64, 187–218.CrossRefGoogle Scholar
Calvo, C. (1968) The crystal structure of graftonite. American Mineralogist, 53, 742–50.Google Scholar
Černý, P., Selway, J.B., Ercit, T.S., Breaks, F.W., Anderson, A.J. and Anderson, S.D. (1998) Graftonite-beusite in granitic pegmatites of the Superior Province: a study in contrasts. The Canadian Mineralogist, 36, 367–376.Google Scholar
De Bruiyn, H., Van der Westhuizen, W.A., Beukes, G.J. and Meyer, T.Q. (1990) Corkite from Aggeneys, Bushmanland, South Africa. Mineralogical Magazine, 54, 603–608.CrossRefGoogle Scholar
Dukino, R.D., England, B.M. and Kneeshaw, M. (2000) Phosphorus distribution in BIF-derived iron ores of Hamersley Province, Western Australia. Institution of Mining and Metallurgy Transactions (Section B: Applied Earth Sciences), 109, B168–B176.Google Scholar
Dukino, R.D., England, B.M. and Kneeshaw, M. (2000) Phosphorus distribution in BIF-derived iron ores of Hamersley Province, Western Australia. Institution of Mining and Metallurgy Transactions (Section B: Applied Earth Sciences), 109, B168–B176.Google Scholar
Floss, C. (2001) Fe,Mg,Mn-bearing phosphates in the GRA 95209 meteorite: occurrence and mineral chemistry. American Mineralogist, 84, 1354–1359.CrossRefGoogle Scholar
Fransolet, A.-M. (1977) Intercroissances et inclusions dans les associations graftonite-sarcopside-triphylite. Bulletin de la Societé Française de Minéralogie et de Cristallographie, 100, 198–207.Google Scholar
Fransolet, A.-M., Keller, P. and Fontan, F. (1986) The phosphate mineral associations of the Tsaobismund pegmatite, Namibia. Contributions to Mineralogy and Petrology, 92, 502–517.CrossRefGoogle Scholar
Hoffmann, D. (1994) Geochemistry and genesis of manganiferous silicate-rich iron formation bands in the Broken Hill deposit, Aggeneys, South Africa. Exploration and Mining Geology, 3, 407–417.Google Scholar
Joubert, P. (1986) The Namaqualand Metamorphic Complex – a summary. Pp. 1395–1420 in: Mineral Deposits of Southern Africa (Anhaeusser, C.R. and Maske, S., editors). Geological Society of South Africa.Google Scholar
Moore, J.M. (1989) A comparative study of metamorphosed supracrustal rocks from the western Namaqualand Metamorphic complex. Bulletin of the Precambrian Research Unit, 37, University of Cape Town, Rondebosch, South Africa.Google Scholar
Moore, J.M., Watkeys, M.K. and Reid, D.L. (1990) The regional setting of the Aggeneys/Gamsberg base metal deposits, Namaqualand, South Africa. Pp. 77–95 in: Regional Metamorphism of Ore Deposits (Spry, A. and Bryndzia, L.T., editors). Springer, Berlin.Google Scholar
Mücke, A., Annor, A. and Neumann, U. (1996) The Algoma-type iron-formation of the Nigerian meta-volcano-sedimentary schist belt. Mineralium Deposita, 31, 113–122.CrossRefGoogle Scholar
Nord, A.G. and Ericsson, T. (1982) The cation distribution in synthetic (Fe,Mn)3(PO4)2 graftonite-type solid solutions. American Mineralogist, 67, 826–832.Google Scholar
Olsen, E. and Fredricksson, K. (1966) Phosphates in iron and pallasite meteorites. Geochimica et Cosmochimica Acta, 30, 459–570.CrossRefGoogle Scholar
Roda, E., Fontan, F., Pesquera, A. and Velasco, F. (1996) The phosphate mineral association of the granitic pegmatites of the Fregeneda area (Salamanca, Spain) Mineralogical Magazine, 60, 767–778.CrossRefGoogle Scholar
Roda, E., Pesquera, A., Fontan, F. and Keller, P. (2001) Phosphate mineral associations of the Aldehuela de la Bóveda Li-Sn-Nb±RTa-bearing pegmatite (Salamanca, Spain). Pp. 477–480 in: Mineral Deposits at the Beginning of the 21st Century (Piestrzynski, A. et al., editors). Balkema, Lisse, The Netherlands.Google Scholar
Rozendaal, A. (1986) The Gamsberg zinc deposit, Namaqualand District. Pp. 1477–1488 in: Mineral Deposits of Southern Africa (Anhaeusser, C.R. and Maske, S., editors). Geological Society of South Africa.Google Scholar
Rozendaal, A. and Stumpfl, E.F. (1984) Mineral chemistry and genesis of Gamsberg zinc deposit, South Africa. Institution of Mining and Metallurgy Transactions (Section B: Applied Earth Sciences), 93, B161–B175.Google Scholar
Smeds, S.-A., Uher, P., Černý, P., Wise, M.A., Gustafsson, L. and Penner, P. (1998) Graftonite-beusite in Sweden: primary phases, products of exsolution, and distribution in zoned populations of granitic pegmatites. The Canadian Mineralogist, 36, 377–394.Google Scholar
Stalder, M. and Rozendaal, A. (2001) The origin of apatite associated with the Gamsberg Zn-Pb deposit, South Africa. Pp. 345–348 in: Mineral Deposits at the Beginning of the 21st Century (Piestrzynski, A. et al., editors). Balkema, Lisse, The Netherlands.Google Scholar
Stanton, R.L. (1976) Petrochemical studies of the ore environment at Broken Hill, NSW 1 – Constitution of ‘banded iron formations’. Institution of Mining and Metallurgy Transactions (Section B: Applied Earth Sciences), 85, B33–B46.Google Scholar
Steele, I.M., Olsen, E., Pluth, J. and Davis, A.M. (1991) Occurrence and crystal structure of Ca-free beusite in the El Sampal IIIA iron meteorite. American Mineralogist, 76, 1985–1989.Google Scholar
Van der Westhuizen, W.A., Strydom, D., Schoch, A.E., Tordiffe, E.A.W. and Beukes, G.J. (1986) Petrochemical evidence on the probable origin of ferriferous metasediments in western Bushmanland. Mineralium Deposita, 21, 121–128.CrossRefGoogle Scholar
Van der Westhuizen, W.A., De Bruiyn, H. and Beukes, G.J. (1990) Dufrenite in iron-formation on the Kangnas farm, Aggeneys district, Bushmanland, South Africa. Mineralogical Magazine, 54, 419–424.CrossRefGoogle Scholar
Wise, M.A. and Černý, P. (1990) Beusite-triphylite intergrowths from the Yellowknife pegmatite field, Northwest Territories. The Canadian Mineralogist, 28, 133–139.Google Scholar
Wise, M.A., Hawthorne, F.C. and Černý, P. (1990) Crystal structure of Ca-rich beusite from the Yellowknife pegmatite field, Northwest Territories. The Canadian Mineralogist, 28, 141–146.Google Scholar