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Beryllium minerals in Cornwall and Devon: helvine, genthelvite, and danalite

Published online by Cambridge University Press:  14 March 2018

Arthur W. G. Kingsbury
Arthur W. G. Kingsbury*
Affiliation:
Department of Mineralogy, University Museum, Oxford
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Summary

Helvine and genthelvite are recorded for the first time in Britain; of the former, three occurrences in Cornwall and one in Devon, and of the latter, one occurrence in Cornwall, are described. British danalite has hitherto been represented by two old specimens with the vague locality ‘Redruth’, Cornwall; occurrences at four Cornish localities are described, and a further Cornish locality is provided by two old specimens previously labelled as garnet. Partial chemical analyses for the helvine, genthelvite, and danalite specimens are presented; helvine and genthelvite occur in pyrometasomatic-hydrothermal deposits in metamorphosed calcareous sediments and, in one instance, in greenstone; danalite in hydrothermal deposits or lodes in metamorphosed greenstone; the parageneses of the three minerals are discussed.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 32 , Issue 255 , December 1961 , pp. 921 - 940
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1961

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References

Page 921 Note 1 Glass, J. J., Jahns, R. H., and Stevens, R. N., Amer. Min., 1944, vol. 29, p. 163.Google Scholar

Page 921 Note 2 See also Neumann, H., Norsk Geol. Tidsskr., 1950, vol. 28, p. 234 Google Scholar. [M.A. 11-511].

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Page 924 Note 1 It was briefly referred to, as an exploration of Black Down in line with Wheal Forest, by Warington Smyth in Trans. Roy. Geol. Soc. Cornwall, 1878, vol. 9, p. 40.

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Page 930 Note 1 The site of the shaft (now cemented over) is 700 yds. north of the western corner of the Redruth Union (Public Assistance) Building.

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Page 932 Note 2 For a short account, see Sir Arthur Russell, Journ. Roy. Inst. Cornwall, 1952, p. 1.

Page 933 Note 1 It was best known for some of the mineral specimens it produced, including, especially, those of chalybite, francolite, cronstedtite, and pseudomorphs of wolframite after scheelite.

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