Hostname: page-component-7479d7b7d-767nl Total loading time: 0 Render date: 2024-07-10T08:25:47.082Z Has data issue: false hasContentIssue false
  • English
  • Français

Magnesium-zinc-spinels from Ceylon

Published online by Cambridge University Press:  14 March 2018

B. W. Anderson  and
C. J. Payne
B. W. Anderson
Affiliation:
Laboratory of the Diamond, Pearl, and Precious Stone Trade Section of the London Chamber of Commerce
C. J. Payne
Affiliation:
Laboratory of the Diamond, Pearl, and Precious Stone Trade Section of the London Chamber of Commerce
Get access Rights & Permissions [Opens in a new window]

Extract

Although the mineral spinel belongs to an isomorphous group, and in the simple formula MgO.Al2O3 a both Mg and A1 are susceptible to isomorphous replacement, yet in the transparent varieties oI gem quality there is, as a rule, very little deviation from the type composition, and the physical properties are moderately constant. In fact, one may say that the only considerable replacement hitherto recorded in spinels used as gemstones is by ferrous iron in the variety known as ceylonite or pleonaste, which is black and opaque even when 7 or 8 % of FeO is present, the end-member of this series being hercynite, FeO.Al2O3, with 41% ferrous oxide.

The purpose of this paper is to draw attention to certain transparent blue spinels from the gem gravels of Ceylon, the physical properties of which differ quite strikingly from those of the normal spinels, from which they are indistinguishable in appearance, magnesium being replaced in this instance not by ferrous iron but by zinc.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 24 , Issue 158 , September 1937 , pp. 547 - 554
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1937

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Page 547 note 1 Rinne, F., Neues Jahrb Min., Abt. A, 1928, Beil.-Bd. 58. p. 43.Google Scholar [Min. Abstr., 4-71.]

Page 548 note 2 Des Cloizeaux, A., Nouvelles recherches ..., Mém. Acad. Sci. Paris, 1867, vol. 18, p. 203 Google Scholar.

Page 548 note 3 Zimányi, K., Zeits. Kryst. Min., 1894, vol. 22, p. 328.Google Scholar

Page 548 note 4 Melczer, G., Zeits. Kryst. Min., 1900, vol. 33, p. 260 Google Scholar.

Page 548 note 5 Bauer, M., Neues Jahrb. Min., 1895, vol. i, p. 281 Google Scholar.

Page 548 note 6 Schlossmacher, K., Zeits. Krist., 1930, vol. 72, p. 468 Google Scholar. [Min. Abstr., 4-255.]

Page 548 note 7 Brauns, R., Deutsche Goldschmiede-Zeitung, 1929, vol. 32, p. 458.Google Scholar

Page 548 note 8 Holgersson, S., Lunds Univ. Årsskrift, 1927, N.F. Avd. 2, vol. 23, no. 9.Google Scholar

Page 549 note 1 Vassar, H. E., Amer. Min., 1925, vol. 10, p, 123.Google Scholar [M.A. 2-487.]

Payne, C. J., Franklin, L., and Anderson, B. W., Gemmologist, 1936, vol. 5, p. 274.Google Scholar [M.A. 6-454.]

Page 551 note 1 Based on Goldschmidt's, V. M. X-ray measurements of the cell side for ZnO.Al2O3, 8.062, and MgO.Al2O3, 8.059Å. (Zeits. Physikal. Chem., Abt. B, 1932, vol. 18. p. 29)Google Scholar, and taking the density of MgO.A12O3 as 3.585. Refractive index as quoted by E. S. Larsen for artificial gahnite (Microscopic determination of the nonopaque minerals, Bull. U.S. Geol. Surv., 1934, no. 848, p. 58).

Page 552 note 1 Schlossmacher, K. and I. Meyer, Zeits. Krist., 1931, vol. 76, p. 377.Google Scholar [M.A. 6-265.]

Page 553 note 1 Wherry, E. T., Amer. Min., 1929, vol. 14, p. 326.Google Scholar [M.A. 4-209.]