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Pennantite, a new manganese-rich chlorite from Benallt mine, Rhiw, Carnarvonshire

Published online by Cambridge University Press:  14 March 2018

W. Campbell Smith ,
F. A. Bannister  and
Max H. Hey
W. Campbell Smith
Affiliation:
Department of Mineralogy, British Museum
F. A. Bannister
Affiliation:
Department of Mineralogy, British Museum
Max H. Hey
Affiliation:
Department of Mineralogy, British Museum
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Extract

The manganese ores of the Benallt mine are pervaded by an orange-coloured mineral which occurs very poorly crystallized as patches and small specks in the matrix. Less commonly it occurs as minute flakes in the ore and sometimes as a constituent of very thin veins which traverse the ore. In some specimens the mineral is better developed. It then shows a good cleavage and resembles in appearance in thin section a weakly pleochroic mica or chlorite. Patches of this mineral in the matrix frequently enclose very small rounded garnets which are believed to be spessartine.

In 1932 Dr. A. F. Hallimond examined some sections of ore from the old Benallt mine for Dr. C. A. Matley and suggested that one of the constituent minerals might be a manganiferous chlorite.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 27 , Issue 194 , September 1946 , pp. 217 - 220
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1946

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References

page 217 note 1 Matley, C. A., Quart. Journ. Geol. Soc. London, 1932, vol. 88, p. 263.CrossRefGoogle Scholar

page 217 note 2 Woodland, A. W., Proc. Geol. Assoc. London, 1939, vol. 50, p. 209.Google Scholar

page 218 note 1 Ganophyllite was found in the neighbouring Nant mine by Sir Arthur Russell in 1911 (this vol., p. 234).

page 218 note 2 Identification confirmed by X-ray photograph and manganese test. Pyrophanite has not previously been recorded from the British Isles.

page 218 note 3 R. Ridgway, Color standards and color nomenclature. 1912.

page 218 note 4 von Engelhardt, W., Zeits. Krist., 1942, vol. 104, p. 145. a 5·37, b 9·30, c 14·10Å., β 97° 20′. [M.A. 3–291.]Google Scholar

page 220 note 1 Hamherg, A., Geol. För. Förh. Stockholm, 1890, vol. 12, p. 580.Google Scholar

page 220 note 2 von Eckermann, H., Geol. För. Förh. Stockholm, 1927, vol. 49, pp. 450–454, and 1944, vol. 66, pp. 721–724. [M.A. 3–474, 0–256.]CrossRefGoogle Scholar

page 220 note 3 Campbell Smith, W., The mineral collection of Thomas Pennant (1726-1798). Min. Mag., 1913, vol. 16, pp. 331–342.CrossRefGoogle Scholar