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On the identity of Poonahlite with Mesolite

Published online by Cambridge University Press:  14 March 2018

H. L. Bowman
H. L. Bowman*
Affiliation:
University of Oxford
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Extract

Among the zeolite specimens from the neighbourhood of Bombay in the Oxford University Collection are several of the well-known type, showing pale green crystals of apophyllite associated with white stilbite and white silky needles labelled as ‘poonahlite’, on a matrix of purplish-brown amygdaloid, with a layer of a bluish-green, earthy mineral lining the amygdules and underlying the zeolites.

The name poonahlite was originally given by H. J. Brooke, in 1831, to a mineral occurring on specimens which he had received from Henry Heuland. He states that the poonahlite formed slender crystals accompanying apophyllite from Poonah, and was at first taken for mesotype or needlestone, but that it had a prism-angle of 92° 20′.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 15 , Issue 70 , July 1909 , pp. 216 - 223
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1909

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References

Page 216 note 1 Brooke, H. J., Phil. Mag., 1881, ser. 2, vol. x, p. 110 Google Scholar. Dufrénoy, A. (‘Traité de Minéralogie,’ 1847, vol. iii, p. 428)Google Scholar wrongly attributes the name to Gmelin, who, however (Ann. Phys. Chem. (Poggendorff), 1840, vol. xlix, p. 538), speaks of it as having been given by Brooke.

Page 217 note 1 In addition to the direct reflections from the faces, the transparent crystals also yield on the goniometer very distinct images by internal reflection at the back faces, and it is possible that these may have led to some confusion in Brooke's measurements.

Page 217 note 2 Gmelin, C. G., Ann. Phys. Chem. (Poggendorff), 1840, vol. xlix, p. 538 CrossRefGoogle Scholar.

Page 217 note 3 Kenngott, G. A., Sitz.-Ber. k. Akad. Wiss. Wien, 1850, vol. v, p. 237 Google Scholar ; Kenngott's Uebers. mineralog. Forschung, for 1850-1, 1853, p. 82 ; Haidinger's Ber., 1851, vol. vii, p. 189.

Page 217 note 4 Some of the Oxford specimens show small globules, whicth, however, are probably gyrolite.

Page 217 note 5 Petersen, T., Neues Jahrb. Min., 1873, p. 852 Google Scholar.

Page 217 note 6 Luedecke, O., Neues Jahrb. Min., 1881, vol. ii, p. 14 Google Scholar.

Page 218 note 1 Hintze, C., ‘Handbuch der Mineralogie,’ 1897, vol. ii, p. 1704 Google Scholar.

Page 218 note 2 The well-known magnificent specimens of stilbite, apophyllite, scolecite, and other zeolites from Poonah, were obtained during the construction of the Great Indian Peninsula Railway. This, however, was not made till 1851, i.e. long after the description of poonahlite by Brooke.

Page 218 note 3 See Genth, F. A., Amer. Journ. Sci., 1854, set. 2, vol. xviii, p. 410 Google Scholar.

Page 218 note 4 Compare Hintze, C., ‘Handbuch tier Mineralogie,’ 1897, vol. ii, p. 1706 Google Scholar.

Page 220 note 1 Görgey, R., Min. Petr. Mitt. (Tschermak), 1908, vol. xxvii, pp. 255–256.Google Scholar

Page 222 note 1 The optic axes of the two parts of the twin will not be parallel, and a comparison of this section with the blue and yellow stripes visible through its side-faces shows that this is the cause of the patches of colour characteristic of the prism-faces.