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A re-examination of churchite

Published online by Cambridge University Press:  14 March 2018

G. F. Claringbull  and
Max H. Hey
G. F. Claringbull
Affiliation:
Department of Mineralogy, British Museum
Max H. Hey
Affiliation:
Department of Mineralogy, British Museum
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Extract

In the course of a study of certain cerium minerals, a spectrogram of churchite was taken and it was noticed that the cerium lines were barely visible, whereas the yttrium lines were very strong. We therefore decided to re-investigate this species.

Churchite was originally described by A. H. Church in 1865, and named by C. G. Williams in the same year. The specimens were collected by R. Talling from an unnamed locality in Cornwall. It has only been analysed once, by Church, who showed it to be a hydrated phosphate of rare-earths and lime; his quantitative data have been recalculated and included in table I. Church obtained qualitative reactions for the cerium group of rare-earths, and for cerium itself, but made no attempt to determine the ratio of cerium to yttrium earths; he assumed a mean molecular weight for the rare-earths which would correspond to R2O3 324, essentially a mixture of cerium earths with but little yttria, but did not adduce any evidence for this assumption.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 30 , Issue 223 , December 1953 , pp. 211 - 217
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1953

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References

Page 211 Note 1 Church, A. H., Chem. News, 1865, vol. 12, no. 302 (September 15), p. 121.Google Scholar Williams, C.G., ibid., no. 307 (October 20), p. 183.Google Scholar Church, A. H., Journ. Chem. Soc. London, 1865, ser. 2, vol 3, p. 259.CrossRefGoogle Scholar

Page 211 Note 2 A solution of the sulphates of the rare-earths gave a precipitate with potassium sulphate ; the oxalate, on ignition, left an orange-brown oxide which dissolved in hydrochloric acid with evolution of chlorine.

Page 211 Note 3 For example, Dana, System of mineralogy 6th edit., 1892, p. 820; 7th edit., 1951, p. 773.

Page 212 Note 1 Henrich, F., Ber. Deutsch. Chem. Gesell., 1922, vol. 55, Abt. B, p. 3013 CrossRefGoogle Scholar (October 14). [M.A. 2-12.] It. Laubmann, Geognost. Jahaubmann, Geognost. Jahreshefte, Geol. Landesunters. München, 1923, vol. 35 (for 1922), p. 193. [M.A. 2-522.] A preliminary note by Henrich, F. appeared in Edel-Erden und -Erze, 1921, vol. 2, p. 181,Google Scholar but the present authors have not been able to see this paper, and it is not clear whether the name weinschenkite appears in it or not.

Page 212 Note 2 Murgoci, G., Compt. Rend. Acad. Sci. Paris, 1922, vol. 175, p. 372 Google Scholar (August 21) and p. 426 (September 4). [M.A. 2-221.]

Page 212 Note 3 Henrich, F., Journ. Prakt. Chem., 1935, vol. 142, p. 1.CrossRefGoogle Scholar

Page 212 Note 4 Strunz, H., Naturwiss., 1942, vol. 30, p. 64.CrossRefGoogle Scholar [M.A. 8-368.] We adopt the setting with β 113° 24' given in Dana (7th edit., vol. 2, p. 772) for the structure cell, and not the setting with β 129° 24' adopted by Strunz. The transformation matrix from Strunz's to our setting is ‖l̄01̄/01̄0/001‖. This setting corresponds to that adopted by Dana (loc. cit.) for gypsum, brushite, and pharmacolite.

Page 212 Note 5 Milton, C., Murata, K. J., and Knechtel, M. M., Amer. Min., 1944, vol. 29, p. 92.Google Scholar [M.A. 9-54.]

Page 215 Note 1 Re-determined on B.M. 40636, H. Strunz's figures yield by the transformation ‖l̄01̄/01̄0/001‖, a 5.46, b 15.12, c 6.28 kX, 113° 24'.

Page 215 Note 2 Transformation Laubmann to present segtings: ‖2̄02̄/01̄0/002‖.

Page 216 Note 1 Larsen, E. S., The microscopic determination of nonopaque minerals. Bull. U.S. Geol. Surv., 1921, no. 679, pp. 58,Google Scholar 168, 217; 2nd edit. by Larsen, E. S. and Berman, H., ibid., 1934, no. 848, pp. 72,Google Scholar 113.