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A new occurrence of zunyite near Postmasburg, South Africa1

Published online by Cambridge University Press:  14 March 2018

Louis T. Nel
Louis T. Nel*
Affiliation:
Geological Survey, Union of South Africa
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Extract

While I was engaged on the geological survey of the Postmasburg manganese fields during 1927 the rare mineral zunyite, a basic orthosilicate of aluminium, was discovered in some altered highly aluminous shales or flagstones. The only occurrence of zunyite so far known is in Colorado, where, according to Dana's ‘System of Mineralogy’, it was found at the Zuñi mine, Anvil Mountain, San Juan Co., and near Red Mountain, Ouray Co.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 22 , Issue 128 , March 1930 , pp. 207 - 221
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1930

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Footnotes

1

This paper collects together the mineralogical details contained in the author's report on ‘The geology of the Postmasburg manganese deposits and the surrounding country’, Geological Survey of the Union of South Africa (Special Publication), Pretoria, 1929, 104 pp. [Min. Abstr., vol. 4, p. 232], with the addition of two new chemical analyses by Mr. H. G. Weall and some other new matter.

References

page 207 note 2 J. D. Dana, System of Mineralogy, sixth edit., 1892, p. 436, and Appendix 1, 1899, p. 75.

page 207 note 3 These two localities are about five miles apart over the county boundary.

page 208 note 1 Schlaepfer, M. and Niggli, P., Zeits. Anorg. Chem., 1914, vol. 87, p. 56.Google Scholar

page 210 note 1 The mineral appears to be one of the leverrierite group, but its determination as such was unsatisfactory.

page 211 note 1 Similar dark red patches were noticed in several diaspore crystals.

page 212 note 1 Corrected values = 2·873 and = 2·884.

page 214 note 1 Reprinted, together with the above analysis (Table II), from the 1929 report (pp. 38-39).

page 215 note 1 W. F. Hillebrand's original (1885) empirical formula H18Al16Si6(O,F,Cl)45 was modified by P. Groth in 1889 (Tab. Übers. Min., 3rd edit., p. 104) as [SiO4]3Al2[Al(OH,F,Cl)2]6, representing a basic orthosilicate analogous to the garnet formula. B. Gossner and F. Mussgnug in 1926, insisting on a ratio Si: A1 = 1:3, gave as alternative formulae SiO2.AlOF.2AlO2H or SiO2.AlF(OH)2.2AlO2H and 2SiO2.2AlOF.3AlO2H.AlO3H3; while later, in order to conform with the results given by X-ray analysis, Gossncr again readjusted the formula to 3SiO2.3AlO(F,Cl).4AlO2H.2AlO3H3.

page 217 note 1 Min. Abstr., vol. 4, p. 232.

page 218 note 1 Haidinger, W., Edinburgh Journ. Sci., 1824, vol. 1, p. 60, pl. 3.Google Scholar

page 218 note 2 A. Sadebeek, Zeits. Deutsch. Geol. Gesell., 1872, vol. 24, p. 427, pls. 16, 17; Angewandte Krystallographie, Berlin, 1876, pl. 3. See also Lewis, W. J., Treatise on Crystallography. Cambridge, 1899, p. 473.Google Scholar

page 220 note 1 E. S. Larsen, Bull U.S. Geol. Survey, 1921, no. 679, p. 160.

page 220 note 2 Matilde Albis, Rend. R. Accad. Lincei, Cl. Sci. Fis., Roma, 1921, ser. 5, vol. 30, sem. 2, p. 472 [Min. Abstr., vol. 2, p. 43]. Determinations are given for six lines: B 1.5975, C 1.5991, D 1.6022, E 1.6048, F 1.6085, G 1.6124, with dispersion, nG-B = 0.0149.

page 220 note 3 B. Gossner and F. Mussgnng, Centralblatt Min., Abt. A, 1926, p. 149 [Min. Abstr., vol. 3, p. 433].

page 220 note 4 Penfield, S. L., Abstract in Min. Mag., 1895, vol. 11, p. 42.Google Scholar