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VII.—On the Formation at Low Temperatures of Certain Fluorides, Silicates, Oxides, Etc., in the Pipernoid Tuff of the Campania

Published online by Cambridge University Press:  01 May 2009

H. J. Johnston-Lavis
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Extract

When such minerals as mica, pyroxene, nepheline, fluorite, and hematite are mentioned to us, we can hardly avoid associating their genesis with very high temperatures, and if amphibole be added we are equally bound to imagine also the existence of high pressure. So deeply rooted is this, I might almost say, superstition that few petrographers, when they find such minerals lining the fissures or cavities in rocks, fail to immediately conclude that great heat, and sometimes pressure, is indicated by such an occurrence. No doubt that in the vast majority of cases they would be right, yet I hope to show in these notes that such minerals have occasionally been produced under little or no pressure at a temperature so low as to be insufficient to carbonize or even discolour the organic matter of bone, that is at a temperature considerably below that of an ordinary baking oven.

Type
Original Articles
Information
Geological Magazine , Volume 2 , Issue 7 , July 1895 , pp. 309 - 314
Copyright
Copyright © Cambridge University Press 1895

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References

page 309 note 1 Brit. Assoc. Rep. 1881, pp. 130–135; quoted by Prestwich, “Controverted Questions of Geology,” pp. 240–241.Google Scholar

page 310 note 1 See H. J. Johnston-Lavis: British Association Reports for 1888 –89–90–92, and Notes on Pipernoid Structure of Igneous Rocks, “Natural Science,” vol. iii, No. 19, September, 1893, pp. 218–221.Google Scholar

page 313 note 1 Johnston-Lavis, H. J., “Relationship of the Structure of Igneous Rocks to the Conditions of their Formation,” Scientific Proc. Royal Dublin Soc., vol. v, n.s., pp. 112–156; also Q.J.G.S., vol. xli, pp. 103 106.Google Scholar

page 313 note 2 Scacchi, A., “Sulle ossa fossile trovate nel tufo dei vulcani fluoriferi della Campania,” Atti dell' Acc. delle Scienze di Napoli 1888, p. 6; and also “La Regione vulcanica fluorifera della Campania,” Mem. del R. Comitato Geoligico Ital., 2nd ediz., Firenze, 1890, p. 34.Google Scholar