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Weathering Sequence and Alteration Products in the Genesis of the Graskop Manganese Residua, Republic of South Africa

Published online by Cambridge University Press:  02 April 2024

Loraine C. Hawker  and
James G. Thompson
Loraine C. Hawker
Affiliation:
Soil and Irrigation Research Institute, Private Bag X79, Pretoria, 0001, Republic of South Africa
James G. Thompson
Affiliation:
Soil and Irrigation Research Institute, Private Bag X79, Pretoria, 0001, Republic of South Africa
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Abstract

Although numerous, small, manganese oxide deposits associated with dolomite in the Eastern Transvaal escarpment, Republic of South Africa, have been known for many years, their mineralogical make-up is somewhat controversial. Chemical, mineralogical, and morphological properties of the weathering products of dolomite and the coexisting manganese oxide material in the Graskop area were therefore determined. Mn and Fe occur only in minor accessory minerals in the original rock; however, in the weathering residue, these elements are concentrated and occur as separate mineral phases, chiefly birnessite, nsutite, and goethite. Thin veins of pure muscovite and quartz traverse the residua. Rare, pure calcite and maghemite nodules were noted throughout the residual manganese material. The properties of this weathering sequence suggest that the manganese wad deposits were formed in situ as a result of the congruent dissolution of dolomite, leaving a porous, sponge-like structure, highly enriched in Mn and Fe oxides.

Keywords

BirnessiteDolomiteInfrared spectroscopyManganeseNsutitePetrographyWadWeatheringX-ray powder diffraction

Information

Type
Research Article
Information
Clays and Clay Minerals , Volume 36 , Issue 5 , October 1988 , pp. 448 - 454
Copyright
Copyright © 1988, The Clay Minerals Society

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References

Brown, G. (1980) Associated minerals: in Crystal Structures of Clay Minerals and their X-ray identification, Brindley, G. W. and Brown, G., eds., Mineralogical Society, London, 362–372.Google Scholar
De Waal, S. A. and Hiemstra, S. A. (1966) X-ray analysis of six samples of manganese ore from Graskop, Eastern Transvaal: Natl. Inst. Metallurgy Kept. 97, 3 pp.Google Scholar
Mehra, O. P., Jackson, M. L. and Swineford, A., 1960 Iron oxide removal from soils and clays by a dithionite-citrate system buffered with sodium bicarbonate Clays and Clay Minerals, Proc. 7th Natl. Conf, Washington D.C., 1958 New York Pergamon Press 317 – 327.Google Scholar
Norrish, K. and Hutton, J. T., 1969 An accurate X-ray spectrographic method for the analysis of a wide range of geological samples Geochim. Cosmochim. Acta 33 431 – 453.CrossRefGoogle Scholar
Potter, R. M. and Rossman, G. R., 1979 The tetravalent manganese oxides: Identification, hydration and structural relationships by infrared spectroscopy Amer. Mineral. 64 1199 – 1218.Google Scholar
Potter, R. M. and Rossman, G. R., 1979 Mineralogy of manganese dendrites and coatings Amer. Mineral. 64 1219 – 1226.Google Scholar
Taylor, R. M. and Schwertmann, U., 1974 Maghemite in soils and its origin. I. Properties and observations of soil maghemites Clay. Miner. 10 289 – 298.CrossRefGoogle Scholar
Turner, S. and Buseck, P. R., 1981 Todorokites: A new family of naturally occurring manganese oxides Science 212 1024 – 1027.CrossRefGoogle ScholarPubMed
Turner, S., Siegel, M. D. and Buseck, P. R., 1982 Structural features of todorokite intergrowths in manganese nodules Nature 296 841 – 842.CrossRefGoogle Scholar