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On rashleighite, a new mineral from Cornwall, intermediate between turquoise and chalcosiderite

Published online by Cambridge University Press:  14 March 2018

Arthur Russell
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Extract

The mineral here described was at first considered to be an iron-rich variety of turquoise and was described by myself as such when this paper was read before the Society in 1937. At that time only a partial analysis had been made; since then Dr. J. A. Smythe of King's College, Newcastle-upon-Tyne, has most kindly undertaken at my instigation careful analyses of the mineral from both of its localities, Bunny mine, St. Austell, and Castle-an-Dinas wolfram mine, St. Columb Major. As a result of these two analyses, which are in close agreement, it is evident that the mineral is a new one, intermediate between turquoise and the two minerals chalcosiderite and andrewsite, and forming a middle member of what is probably an isomorphous group.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 28 , Issue 202 , September 1948 , pp. 353 - 358
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1948

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References

page 354 note 1 Graham, A. R. and Berry, L. G., Amer. Min., 1947, vol. 32, p. 201 (abstract);Google Scholar Graham, A. R., Univ. Toronto Studies, Geol. Ser., 1948, no. 52 (for 1947), p. 39. [M.A. 10–336.]Google Scholar

page 355 note 1 The name Bunny was used by the early Cornish miners to signify a kind of stockwork or ramification of veinlets of ore. Pryce, W., Mineralogia Cornubiensis, 1778, p. 317 Google Scholar, defines it as ‘A pipe of Ore. A great collection of Ore without any vein coming into or going from it’; either tin or copper ore. John Hawkins, On the stratified deposits of tin-stone, called tin-floors, &c. (Trans. Roy. Geol. Soc. Cornwall, 1822, vol. 2, p. 33), describes such a deposit at Botallack mine, St. Just, which was known as Grylls's bunny. At Bunny mine there are two large rudely circular pits adjoining one another, the site of ancient workings on a ramification of tin veinlets in the kaolinized granite and not to be confused with the numerous china-clay pits in their immediate neighbourhood. The comparatively modern underground mine workings are situated on the ground between these two pits.

page 357 note 1 Mention of this as ‘an as yet undetermined phosphate of alumina’ is made in Min. Mag., 1925, vol. 20, p. 233.

page 357 note 2 Russell, A., Min. Mag., 1938, vol. 25, p. 54.Google Scholar In an article on the Castle-an-Dinas mine by Trounson, J. H. (Mining Mag. London, 1940, vol 63, p. 20)Google Scholar the mineral is referred to as variscite.

page 358 note 1 Lacroix, A., Minéralogie de la France et de ses Colonies, 1901–1909, vol. 3, pp. 228–229, and 1910, vol. 4, p. 530.Google Scholar