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Topaz from Cornwall, with an account of its localities

Published online by Cambridge University Press:  14 March 2018

Arthur Russell
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Extract

Topaz, so common an accessory in tin lodes in all parts of the world, has hitherto been looked upon as comparatively rare in Cornwall. When massive, or even in the form of small, well-developed crystals, it is a mineral easily overlooked, or apt cursorily to be mistakcn for quartz.

The presence of topaz as a microscopic accessory in granite, greisen, and rarely elvans, from most of the Cornish masses, has been determined by Dr. J. S. Flett in the course of the work of the Geological Survey; while the late Mr. J. H. Collins was responsible for the record of other interesting localities.

In the present notes I have collected all the available information respecting its mode of occurrence and localities ; and have added several new ones, at some of which the mineral occurs in considerable mass, thus affording evidence that topaz is in Cornwall, as in the case of other countries, a comparatively common associate of cassiterite and wolframite, both in granite and sedimentary rocks.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 20 , Issue 106 , June 1924 , pp. 221 - 236
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1924

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References

Page 223 note 1 Davy, Sir Humphry, Hints on the geology of Cornwall. Trans. Roy. Geol. Soc. Cornwall, 1818, vol. 1, p. 41 Google Scholar.

Page 223 note 2 Forbes, J., On the geology of St. Michael's Mount. Trans. Roy. Geol. Soc. Cornwall, 1822, vol. 2, p. 370 Google Scholar.

Page 224 note 1 Collins, J. H., Mineralogy of Cornwall and Devon. 1871, part 2t p. 101 Google Scholar.

Page 224 note 2 Mem. Geol. Survey, Land's End district, 1907, p. 53.

Page 225 note 1 Collins, J. H., On Cornish tin-stones and tin-capels, Min. Mag., 1882, vol. 5, p. 125 Google Scholar.

Page 225 note 2 Ibid., Observations on the West of England mining region. 1912, p. 75.

Page 225 note 3 Garby, J., A catalogue of minerals found in Cornwall, with their localities. Trans. Roy. Geol. Soc. Corasvall, 1848, vol. 7, p. 78 Google Scholar.

Page 225 note 4 Mem. Geol. Survey, Land's End district, 1907, p. 53.

Page 225 note 5 Ibid., Falmouth, Truro, Camhorne, and Redruth, 1906, p. 53.

Page 225 note 6 Ibid., p. 57.

Page 226 note 1 Scrivenor, J. B., The granite and greisen of Cligga Head (western Cornwall). Quart. Journ. Geol. Soc. London, 1903, vol. 59, pp. 142–159 CrossRefGoogle Scholar.

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Page 230 note 2 Hogg, T., Manual of Mineralogy. 1825, p. 156 Google Scholar.

Page 230 note 3 Collins, J. H., Mineralogy of Cornwall and Devon. 1871, part 2, p. 101 Google Scholar

Page 230 note 4 Mem. Geol. Survey, Newquay, 1906, pp. 36-38 and 63.

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Page 232 note 1 South of Castle-an-Dinas Hill there is another old mine known as Castle-an-Dinas mine ; this was worked for tin on a continuation of the stanniferous elvan which traverses Belowda Hill mine.

Page 232 note 2 Davison, E. H., The geology of Castle-an-Dinas and Belowda Beacon. Trans. Roy. Geol. Soc. Cornwall, vol. 19. On the geology of Castle-an-Dinas wolfram mine. Geol. Mug., 1920, vol. 57, pp. 347–351 Google Scholar [Min. Abstr., vol. 1, p. 387].

Page 233 note 1 Collins, J. H. and Coon, J. M., On the topaz rock of St. Mewan Beacon, Cornwall. Trans. Roy. Geol. Soc. Cornwall, 1915, vol. 15, pp. 1–12 [Min. Abstr., vol. 1, p. 92.]Google Scholar

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Page 234 note 2 J. H. Collins and J. M. Coon, 1915, loc. cit.

Page 235 note 1 Collins, J. H., A list of minerals found in Cornwall and Devon. Journ. Roy. Inst. Cornwall, 1911, vol. 18, p. 459 Google Scholar

Page 235 note 2 J. H. Collins and J. M. Coon, 1915, loc. cir.

Page 235 note 3 Collins, J. H., The Hensbarrow granite district. Truro, 1878, p. 41 Google Scholar.

Page 235 note 4 Mem. Geol. Survey, Bodmin and St. Austell, 1909, pp. 58 and 111.

Page 235 note 5 Le Neve Foster, G., On some tin stockworks in Cornwall. Quart. Journ. Geol. Soc. London, 1878, vol. 3, pp. 655–656 Google Scholar.

Page 236 note 1 Mem. Geol. Survey, Padstow and Camelford, 1910, pp. 54 and 60.