Hostname: page-component-cd9895bd7-p9bg8 Total loading time: 0 Render date: 2024-12-27T08:14:03.342Z Has data issue: false hasContentIssue false
  • English
  • Français

Zirconolite, chevkinite and other rare earth minerals from nepheline syenites and peralkaline granites and syenites of the Chilwa Alkaline Province, Malawi

Published online by Cambridge University Press:  05 July 2018

R. G. Platt ,
F. Wall ,
C. T. Williams  and
A. R. Woolley
R. G. Platt
Affiliation:
Dept. of Geology, Lakehead University, Thunder Bay, Ontario, Canada
F. Wall
Affiliation:
Dept. of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K.
C. T. Williams
Affiliation:
Dept. of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K.
A. R. Woolley
Affiliation:
Dept. of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

Five rare earth-bearing minerals found in rocks of the Chilwa Alkaline Province, Malawi, are described. Zirconolite, occurring in nepheline syenite, is unusual in being optically zoned, and microprobe analyses indicate a correlation of this zoning with variations in Si, Ca, Sr, Th, U, Fe, Nb and probably water; it is argued that this zoning is a hydration effect. A second compositional zoning pattern, neither detectable optically nor affected by the hydration, is indicated by variations in Th, Ce and Y such that, although total REE abundances are similar throughout, there appears to have been REE fractionation during zirconolite growth from relatively heavy-REE and Th-enrichment in crystal cores to light-REE enrichment in crystal rims.

Chevkinite is an abundant mineral in the large granite quartz syenite complexes of Zomba and Mulanje, and analyses are given of chevkinites from these localities. There is little variation in composition within each complex, and only slight differences between them; they are all typically light-REE-enriched. The Mulanje material was shown by X-ray diffraction to be chevkinite and not the dimorph perrierite, but chemical arguments are used in considering the Zomba material to be the same species. Other rare earth minerals identified are monazite, fluocerite and bastnäsite. These are briefly described and microprobe analyses presented.

Keywords

zirconolitechevkinitemonazitefluoceritebastnäsiteChilwa Alkaline ProvinceMalawi
Type
Mineralogy
Information
Mineralogical Magazine , Volume 51 , Issue 360 , June 1987 , pp. 253 - 263
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1987

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

Åmli, R., and Griffin, W.L. (1975) Microprobe analyses of REEminerals using empirical corrections. Am. Mineral., 60, 559-606.Google Scholar
Borodin, L.S., Bykova, A.B., Kapitonova, T.A., and Pyatenko, Yu. A. (1960) New data on zirconolite and its niobium variety. DokL Acad. Sci. USSR, Earth Sci. Sect., 134, 1022-4.Google Scholar
Calvo, C., and Faggiani, R. (1974) A re-investigation of the crystal structures of chevkinite and perrierite. Am. Mineral., 59, 1277-85.Google Scholar
Fleischer, M. (1978) Relative proportions of the lanthanides in minerals of the bastnaesite group. Can. Mineral., 16, 361-3.Google Scholar
Fleischer, M. and Altschuler, Z.S. (1969) The relationship of the rare-earth composition minerals to geological environment. Geochim. Cosmochim. Acta, 33, 725-32.CrossRefGoogle Scholar
Fowler, M.B., and Williams, C.T. (1986) Zirconolite from the Glen Dessarry syenite; a comparison with other Scottish localities. Mineral. Mag., 50, 326-8.CrossRefGoogle Scholar
Frondel, J.W. (1975) Lunar Mineralogy, Wiley-Interscience, New York, 323 pp.Google Scholar
Gatehouse, B.M., Grey, I.E., Hill, R.J., and Rossell, H.J. (1981) Zirconolite, CaZrxTi3∼O7; structure refinements for near end-member compositions with x = 0.85 and 1.30. Acta Crystallogr. B37, 306-12.CrossRefGoogle Scholar
Gmelin Handbook of Inorganic Chemistry (AS, t984) Y, La, and the Lanthanoids: Minerals (Silicates). Deposits. Mineral Index. (I. Kubach, ed.). Springer-Verlag, 248 pp.Google Scholar
Ito, J. (1967) A study of chevkinite and perrierite. Am. Mineral., 52, 1094-104.Google Scholar
Ito, J. and Arem, J.E. (1971) Chevkinite and perrierite: synthesis, crystal growth and polymorphism. Ibid. 56, 307-19.Google Scholar
Kesson, S.E., and Ringwood, A.E. (1983) Safe disposal of spent nuclear fuel. Rad. Waste Manag. and the Nucl. Fuel Cycle, 4, 159-74.Google Scholar
Sinclair, W.J., and Ringwood, A.E. (1983) Solid solution limits in SYNROC zirconolite. Nuel. Chem. Waste Manag. 4, 259-65.Google Scholar
Mazzi, F., and Munno, R. (1983) Calciobetafite (new mineral of the pyrochlore group) and related minerals from Campi Flegrei, Italy; crystal structures of polymignyte and zirkelite: comparison with pyrochlore and zirconolite. Am. Mineral., 68, 262-76.Google Scholar
Mitchell, R.S. (1973) Metamict minerals: a review. Part II. Origin of the metamictization, methods of analysis, miscellaneous topics. Mineral. Record, 4, 214-23.Google Scholar
Platt, R.G., and Woolley, A.R. (1986) The mafic mineralogy of the peralkaline syenites and granites of the Mulanje complex, Malawi. Mineral. Mag., 50, 85-99.CrossRefGoogle Scholar
Purtscheller, F., and Tessadri, R. (1985) Zirconolite and baddelyite from metacarbonates of the Oetztal-Stubai complex (northern Tyrol, Austria). Ibid. 49, 523-9.Google Scholar
Raber, E., and Haggerty, S.E. (1979) Zircon oxide reactions in diamond-bearing kimberlites. In Kimberlites, diatremes and diamonds: their geology, petrology and geochemistr. (F. R. Boyd and H. O. A. Meyer, eds). Proc. Sec. Int. Kimberlite Conf., 1, 229-40.Google Scholar
Reed, S.J. B. (1986) Ion microprobe determination of rare earth elements in accessory minerals. Mineral. Mag., 50, 315. Ringwood, A.E. (1985) Disposal of high-level nuclear wastes: a geological perspective. Ibid. 49, 159-76.CrossRefGoogle Scholar
Roeder, P.L. (1985) Electron microprobe analysis of minerals for rare-earth elements: use of calculated peak-overlap corrections. Can. Mineral, 23, 263-71.Google Scholar
Segalstad, T.V., and Larsen, A.O. (1978) Chevkinite and perrierite from the Oslo region, Norway. Am. Mineral, 63, 499-505.Google Scholar
Shannon, R.D., and Prewitt, C.T. (1969) Effective ionic radii in oxides and fluorides. Acta Crystallogr., B25, 925-46.Google Scholar
Sinclair, W., and Ringwood, A.E. (1981) Alpha-recoil damage in natural zirconolite and perovskite. Geochem. J., 15, 229-43.CrossRefGoogle Scholar
Vlasov, K.A. (1966) In Geochemistry and Mineralogy of Rare Elements and Genetic Types of their Deposits, Volume II, Mineralogy of the Rare elements (K. A. Vlasov, ed.). Israel Program for Scientific Translations, Jerusalem, 945 pp.Google Scholar
Wakita, H., Rey, P., and Schmitt, R.A. (197l) Abundances of the 14 rare earth elements and 12 other rare elements in Apollo 12 samples: five igneous and one breccia rocks and four soils. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta Suppl. 2 (2), 1319–29.Google Scholar
Wark, D.A., Reid, A.F., Lovering, J.F., and E1 Goresy, A. (1973) Zirconolite (versus zirkelite) in lunar rocks (abstract). In Lunar Science IV (J. W. Chamberlain and Watkins, eds). Lun. Sci. Inst. Houston, 764–6.Google Scholar
White, T.J. (1984) The microstructure and microchemistry of synthetic zirconolite, zirkelite and related phases. Am. Mineral., 69, 1156-72.Google Scholar
Williams, C.T. (1978) Uranium-enriched minerals in mesostasis areas of the Rhum layered pluton. Contrib. Mineral. Petrol., 66, 29-39.CrossRefGoogle Scholar
Woolley, A.R., and Garson, M.S. (1970) Petrochemical and tectonic relationship of the Malawi carbonatiticalkaline province and the Lupata-Lebomba volcanics. In African Magmatism and Tectonics (T. N. Clifford and I. G. Gass, eds.). Oliver and Boyd, Edinburgh, 237-62.Google Scholar
Woolley, A.R., and Garson, M.S.and Platt, R.G. (1986) The mineralogy of nepheline syenite complexes from the northern part of the Chilwa Province, Malawi. Mineral. Mag., 50, 597-610.CrossRefGoogle Scholar