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The temperature-range of formation for tourmaline, rutile, brookite, and anatase in the Dartmoor granite

Published online by Cambridge University Press:  14 March 2018

A. Brammall  and
H. F. Harwood
H. F. Harwood
Affiliation:
Imperial College of Science and Technology, London
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Extract

The range of temperature within which tourmaline can arise in nature has not hitherto been determined. No synthesis of this mineral is on record, and experimental data are therefore lacking. On the other hand, rutile, brookite, and anatase have all been prepared synthetically, and the experimental data suggest their rutile is formed at the highest temperatures, brookite at temperatures considerably lower, and anatase at a point still lower on the scale. It is generally conceded that for rutile a pyrogenic origin is possible, and that brookite and anatase appear only as secondary minerals. The status of tourmaline as a possible pyrogenic mineral is regarded as doubtful by Clarke, who states that' in igneous rocks tourmaline seems to have been produced by fumarole action, and not as a direct separation from the magma'.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 21 , Issue 116 , March 1927 , pp. 205 - 220
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1927

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References

page 205 note 1 F. W. Clarke, ‘The data of geochemistry', 1924, p. 417.

page 205 note 2 Wright, F. E. and Larsen, E. S., ‘Quartz as a geologic thermometer’. Amer. Journ. Sci., 1909, ser. 4, vol. 27, pp. 421–447 Google Scholar.

page 206 note 1 P. Quensel, Centralblatt Min., 1906, p. 728.

page 206 note 2 A. L. Day and E. S. Shepherd, Amer. Journ. Sci., 1906, ser. 4, vol. 22, p. 276.

page 206 note 3 F. Einne and E. Kolb, Neues Jahrb. Min., 1910, vol. ii, p. 138.

page 206 note 4 J. Koenigsbevger and W. J. Müler, Centralblatt Min., 1906, p. 371.

page 206 note 5 White, W. P., Amer. Journ. Sci., 1919, ser. 4, vol. 47, p. 1 CrossRefGoogle Scholar.

page 206 note 6 Gibbs, R. E., ’The polymorphism of silicon dioxide and the structure of tridymite’. Proc. Roy. Soc. London, Ser. A, 1926, vol. 113, pp. 351-368 Google Scholar.

page 206 note 7 Wyckoff, R. W. G., ‘The crystal structure of the high temperature (β-) modification of quartz’. Amer. Journ. Sci., 1926, ser. 5, vol. 11, pp. 101–112. [Min. Abstr., vol. 3, p. 183.]CrossRefGoogle Scholar

page 208 note 1 Cited by F. W. Clarice, loc. cit, pp. 361-366.

page 208 note 2 K. Chrustschoff, Amer. Chemist, 1878, vol. 3, p. 281 ; Compt. Rend. Acad. Sci. Paris, 1887, vol. 104, p. 602 ; Neues Jahrb. Min., 1897, vol. i, p. 240.

page 208 note 3 Summarized by F. W. Clarke, loc. cit., p. 355.

page 208 note 4 Described and discussed by F. W. Clarke, loc. cit, pp. 354-356.

page 208 note 5 B. Doss (Neues Jahrb. Min., 1894, vol. ii, p. 147) fused titanic oxide in beads of either microcosmic salt or borax in a loop of platinum wire. Anatase was produced only in the beads of microcosmic salt; borax beads yielded only rutile. The crystals of anatase were too minute (0.l mm.) for accurate gonio metric measurement, and were identified on the evidence of chemical tests and of angles measured by means of the microscope.

page 209 note 1 When a liquid (e. g. water, critical temperature 374°) containing a dissolved salt is heated above its critical temperature the salt is also volatilized. ( Vogt, J. H. L., Econ. Geol., 1926, vol. 21, p. 218 Google Scholar.)

page 209 note 2 Bowen, N. L., ‘The reaction relation in petrogenesis’. Journ. Geol., 1922, vol. 30, pp. 177-198.Google Scholar

page 211 note 1 Dartmoor biotite contains up to 1-9 % of titanic oxide.

page 212 note 1 Brammall, A. and Harwood, H. F., ‘The occurrence of rutile, brookite, and anatase on Dartmoor’. Min. Mag., 1923, vol. 20, p. 22 Google Scholar, foot-note references.

page 213 note 1 Brammall, A. and Harwood, H. F., ‘Tourmalinization in the Dartmoor granite’. Min. Mag., 1925, vol. 20, pp. 319–330 Google Scholar.

page 215 note 1 Such rutile needles in chloritized biotite are also described (with an excellent iigure) by E. E. Lowe,’ The igneous rocks of the Mountsorrel district'. Leicester Lit. Phil. Soc, 1926, p. 10, fig. 3.

page 218 note 1 Such tourmaline, in the form of extremely minute pale greenish hemimorphic prisms, has been observed in the Skiddaw Slate and in certain Bolivian phyllites. A. Brammall, ‘ Reconstitution processes in shales, slates, and phyllites’. Min. Mag., 1921, vol. 19, pp. 211-224.

page 218 note 2 P. Hautefeuille (1865), cited by Clarke, loc. cit., pp. 354-355.

page 218 note 3 Quartz is unstable at all temperatures above 800° (Day and Shepherd, loc. cit.), is metastable above 870° (White, loc. cit., p. 30), is transformed to tridymite at 870° ± 10° ( Fenner, C. N., Amer. Journ. Sci., 1913, ser. 4, vol. 36, p. 331 Google Scholar), tridymite passing over to cristobalite at 1470° ± 10° (Fenner).