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Exotic aluminium phosphates, natromontebrasite, brazilianite, goyazite, gorceixite and crandallite from rare-element pegmatites in Namibia

Published online by Cambridge University Press:  05 July 2018

J. R. Baldwin ,
P. G. Hill ,
O. von Knorring  and
G. J. H. Oliver
J. R. Baldwin*
Affiliation:
Crustal Geodynamics Group, School of Geography and Geosciences, University of St Andrews, KY16 9AL, UK
P. G. Hill
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, EH9 3JW, UK
O. von Knorring
Affiliation:
Department of Earth Sciences, University of Leeds LS2 9JT, UK
G. J. H. Oliver
Affiliation:
Crustal Geodynamics Group, School of Geography and Geosciences, University of St Andrews, KY16 9AL, UK
*
*E-mail: [email protected]
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Abstract

Replacement phenomena in amblygonite–montebrasite in rare-element pegmatites from the Karibib-Usakos area, Namibia, have been investigated using the electron microprobe. The first African occurrence and analysis of the very rare mineral natromontebrasite NaAl(PO4)(OH,F) is reported from the Daheim pegmatite. In the Okatjimukuju pegmatite, montebrasite has been replaced by a number of phases including crandallite CaAl3(PO4)2(OH)5·H2O and brazilianite NaAl3(PO4)2(OH)4. In one example, montebrasite has been almost completely replaced by brazilianite which has also been found to contain not only crandallite but also its solid solution analogues: goyazite SrAl3(PO4)2(OH)5·H2O and gorceixite BaAl3(PO4)2(PO3OH)(OH)6. Apatite is common at the contacts with montebrasite and associated minerals and texturally is intimately intergrown with crandallite, goyazite and gorceixite at Okatjimukuju. The occurrence of these minerals offers insight into the chemistry of post-magmatic fluids in these pegmatites.

Keywords

Namibiaexotic aluminium phosphateslithium pegmatitespost-magmatic fluids
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 6 , December 2000 , pp. 1147 - 1164
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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Footnotes

†

Deceased

References

Baldwin, J.R. (1993) Lithium and tantalum mineralzation from rare-element pegmatites in Southern Africa. PhD thesis, Univ. St. Andrews, UK.Google Scholar
Burt, D.M. and London, D. (1982) Subsolidus equilibria. Pp. 329-346 in: Granitic Pegmatites in Science and Industry (Černý, P., editor ). Mineralogical Association of Canada, Short Course Handbook, 8.Google Scholar
Cerna, I., Černý, P. and Ferguson, R.B. (1972) The Tanco pegmatite at Bernic Lake, Manitoba. III. Amblygonite– montebrasite. Canad. Mineral., 11, 643–59.Google Scholar
Coetzee, G.L. and Edwards, C.B. (1959) The geology of the Mrima carbonatite, Kenya. Trans. Geol. Soc. South Africa, 62, 373.Google Scholar
Dana, J.D. (1963) System of Mineralogy, Vol. 2, 7th edition. Palache, C., Berman, H. and Frondel., C. John Wiley, New York.Google Scholar
Dubois, J., Marchant, J. and Bourguignon, P. (1973) Données mineralogique sur la serie amblygonite-montebrasite. Annales Soc. Geol. Belgique, 95, 285-310.Google Scholar
Fisher, D.J. (1958) Pegmatite phosphates and their problems. Amer. Mineral., 43, 181-207.Google Scholar
Fleischer, M. (1987) Glossary of Mineral Species. 5th edition. Mineral Data Publishing, Tucson, Arizona, USA.Google Scholar
Garcon, M. (1962) The Tundulu Carbonatite Ring-Complex in Southern Nyasaland. Geol. Surv. Nyasaland, Memoir No. 2.Google Scholar
Hawthorne, F.C. (1998) Structure and chemistry of phosphate minerals. Mineral. Mag., 62, 141–64.CrossRefGoogle Scholar
Jahns, R.H. (1982) Internal evolution of granitic pegmatites. Pp. 293-346 in: Granitic Pegmatites in Science amd Industry (Černý, P., editor). Mineralogical Association of Canada, Short Course Handbook, 8.Google Scholar
Jahns, R.H. and Burnham, C.W. (1969) Experimental studies of pegmatite genesis. I. A model for the derivation and crystallizati on of granites and pegmatites. Econ. Geol., 64, 843–64.CrossRefGoogle Scholar
Kallio, P. (1978) A new X-ray method for the estimation of fluorine content in montebrasite. Amer. Mineral., 63, 1249–51.Google Scholar
Keller, P. and von Knorring, O. (1989) Pegmatites at the Okatjimukuju farm, Karibib, Namibia PART I; Phosphate mineral associations of the Clementine II pegmatite. Eur. J. Mineral., 1, 567–93.CrossRefGoogle Scholar
Korzhinskii, D.S. (1957) Physicochemical basis of the analysis of the paragenesis of minerals. Isvestiya Akademic Nauk. SSSR, Moscow (translated by Consult Bureau. New York, 1959).Google Scholar
London, D. (1984) Experimental phase equilibria in the system LiAlSiO4-SiO2-H2O; a petrogenetic grid for lithium-rich pegmatites. Amer. Mineral., 69, 995-1004.Google Scholar
London, D. (1990) Internal differentiation of rare-element pegmatites, a synthesis of recent research. Geolological Society of America, Spec. Paper, 246.Google Scholar
London, D. (1992) The application of experimental petrology to the genesis and crystallization of granitic pegmatites. Canad. Mineral., 30, 499-540.Google Scholar
London, D. and Burt, D.M. (1982 a) Lithium minerals in pegmatites. Pp. 99-133 in: Granitic Pegmatites in Science and Industry (CÏerný, P., editor ). Mineralogical Association of Canada, Short Course Handbook, 8.Google Scholar
London, D. and Burt, D.M. (1982 b) Lithium aluminosilicate occurrences in pegmatites and the lithium aluminosilicate phase diagram. Amer. Mineral., 67, 483–93.Google Scholar
London, D. and Burt, D.M. (1982 c) Alteration of spodumene, montebrasite and lithiophilite in pegmatites of the Picacho district, Arizona. Amer. Mineral., 67, 97-113.Google Scholar
London, D., CÏerný, P., Loomis, J.L, and Pan, J.J. (1990) Phosphorus in alkali feldspars of rare-element granitic pegmatites. Canad. Mineral., 28, 771–86.Google Scholar
McKie, D. (1963) Goyazite and florencite from two African carbonatites. Mineral. Mag., 36, 281–97.Google Scholar
Mrose, M. (1971) Lacroixite, its redefinition and new occurrences. 20th Annual Meeting of the Clay Minerals Society, Black Hills. Abstr. Prog., 10.Google Scholar
Moore, P.B. (1973) Pegmatite phosphates: Mineralogy and crystal chemistry. Mineral. Rec., 4, 103–30.Google Scholar
Muñez, J.L. and Eugster, H.P. (1969) Experimental control of fluorine reactions in hydrotherma l systems. Amer. Mineral., 54, 943–59.Google Scholar
Pecora, W.T. and Fahey, J.J. (1949) The Corrego Frio pegmatite, Minas Gerais: Scorzalite and souzalite, two new phosphate minerals. Amer. Mineral., 34, 83.Google Scholar
Pouchou, J. and Pichoir, F. (1991) Quantitative analysis of homogeneous or stratified microvolumes applying the model “PAP”. Pp. 31-75 in: Electron Probe Quantitative Analysis (Heinrich, K.F.J. and Newbury, D.E., edsitors). Plenum Press, New York, USA.CrossRefGoogle Scholar
Pough, F.H. and Henderson, E.P. (1945) Brazilianite, a new phosphate mineral. Amer. Mineral., 30, 572–82.Google Scholar
Schaller, W.T. (1911) Natramblygonite, a new mineral. Amer. J. Sci., 31, 48-50.CrossRefGoogle Scholar
von Knorring, O. (1985) Some mineralogical, geochemical and economic aspects of lithium pegmatites from the Karibib-Cape Cross pegmatite field in South West Africa/Namibia. Comm. Surv. SW Africa/Namibia, 1, 79–84.Google Scholar