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Russellite, a new British mineral

Published online by Cambridge University Press:  14 March 2018

Max H. Hey ,
F. A. Bannister  and
Arthur Russell
Max H. Hey
Affiliation:
Mineral Department of the British Museum
F. A. Bannister
Affiliation:
Mineral Department of the British Museum
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Extract

In May, 1936, a quantity of pale yellow, rounded fragments, averaging 7 mm. across, was submitted to us by Mr. Arthur Russell for examination, with the information that the material came from the Castle-an-Dinas wolfram mine, and contained bismuth and tungsten. Chemical and spectroscopic examination showed that, besides bismuth and tungsten, the mineral contained only traces of silicon, arsenic, and iron. A sample of the same material had also been given to the British Museum by Mr. E. H. Davison in 1934 and registered provisionally as bismuth tungstate. This, however, would not have provided sufficient of the yellow mineral for chemical analysis. We are also indebted to Mr. Davison for a further generous supply of yellow pellets picked from the wolfram concentrates received since tile present work was begun. The mineral has all the attributes of an alteration product probably of native bismuth. It is fine-grained and compact, with hardness 3½, and on fracture it gives a clay-like odour. Some of the pellets show traces of a micaeeous mineral and quite frequently enclose native bismuth, wolframite, and bismuthinite. Mr. Russell has picked out from tihe material he had collected a few green pellets and some showing both the yellow and the green mineral. Spectrographs of the two are identical, but an X-ray powder photograph of the green mineral is quite distinct from that of tile yellow mineral.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 25 , Issue 161 , June 1938 , pp. 41 - 55
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1938

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References

page 42 note 1 Muir, M. M. P. and Hutchinson, A., Journ. Chem. Soc. London, 1889, vol. 55, p. 143.CrossRefGoogle Scholar The X-ray photographs obtained from this substance indicate that it is a definite compound, quite distinct from ordinary Bi2O3.

page 42 note 2 Zambonini, F., Gazzetta Chimica Italiana, 1920, vol. 50, pt. 2, pp. 129 and 169 [M.A. 2–245.]Google Scholar

page 43 note 1 Bannister, F. A. and Hey, M. H., Min. Mag., 1938, vol. 25, p. 30.CrossRefGoogle Scholar

page 45 note 1 This is not, proved, at least for the natural mineral; a large part of the water might be present as ‘zeolitic’ water of crystallization in the vacant spaces of the structure, and its expulsion would not appreciably affect the X-ray photographs.

page 46 note 1 If it is assumed that the symmetry is lower than D 4k, the range of possible positions of the oxygen atoms is little affected. The more symmetrical assumption is made here as there is no evidence against it.

page 47 note 1 Values of v less than 0·27 have been rejected since they would lead to bismuth-oxygen distances less than 2·32 Å., which is the distance found in the oxyhalides of bismuth ( Bannister, F. A., Min. Mag., 1935, vol. 24, p. 53 CrossRefGoogle Scholar).

page 48 note 1 If 16 oxygen atoms per unit cell were asumed for russellite, the specific gravity should be 9·8, which differs from the experimental value by far more thart the probable experimental error.

page 49 note 1 It was thought at first that cubic Bi2O3 a might be an end-member of the series, but comparison of the X-ray photographs disproves this. It is not unknown for a mixed crystal to have a structure unstable in either of the pure components.

page 50 note 1 Davison, E. H., On the geology of Castle-an-Dinas and Belowda Beacon. Trans. Roy. Geol. Soc, Cornwall, 1919, vol. 15, pp. 269–285. On the geology of Castle-an-Dinas wolfram mine. Geol. Mag. London, 1920, vol. 57, pp. 347–351. [M.A. 1–387.]Google Scholar

page 50 note 2 Russell, A., Topaz from Cornwall, with an account of its localities. Min. Mag., 1924, vol. 20, pp. 231–233.CrossRefGoogle Scholar