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A radioactive mineral from Mozambique related to davidite

Published online by Cambridge University Press:  14 March 2018

F. A. Bannister  and
J. E. T. Horne
F. A. Bannister
Affiliation:
Department of Mineralogy, British Museum
J. E. T. Horne
Affiliation:
Geological Survey and Museum London1
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Extract

Early in 1947 a black, opaque, radioactive mineral resembling samarskite in appearance was discovered at Mavnzi in the Tete distrier of Mozambique, Portuguese East Africa. Two small specimens, one a rough twinned crystal with trigonal symmetry (fig. 3), were sent by h. M. Macgregor; then Director of the Geological Survey of Southern Rhodesia, to the British Museum (Natural History) for investigation, and a chemical analysis by E. Golding (table I, no. 2) followed later in the same year. X-ray photographs of fragments and powder from both specimens were taken, but revealed on development no diffraction spots, lines, or haloes. Only after prolonged heat-treatment could powder lines characteristic of crystalline material be obtained. The metamict nature of the mineral before heat-treatment is not unexpected in view of its chemical composition, optical isotropy, and glassy fracture.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 29 , Issue 209 , June 1950 , pp. 101 - 112
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1950

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References

Page 102 note 1 D. Mawson, Mineral Notes. Trans. Roy. Soc. South Australia, 1916, vol. 40, pp. 262–266; The nature and occurrence of uraniferous mineral deposits in South Australia. Ibid., 1944, vol. 68, pp. 334–357. [M.A. 1–69, 9–250.]

Page 107 note 1 On this assumption the age is estimated to be about 565 million years, in agreement with the geological age of the deposit, which is pre-Karroo and probably pre-Cambrian.

Page 107 note 2 S. Samson and L. G. Sillén, Die Kristallstruktur des Bariumuranates. Nichtcxistenzdcr UO4- Gruppe. Arkiv Kemi, Min.Geol., 1948, vol.25A, no.21. (M.A. 10--539.)

Page 110 note 1 Ilmenites (B.M. 90156) from Ingelsberg, Salzburg, and (B.M. 37302) from Ilmen Mts., Russia. when heated in air for 24 hours at 1000° C. yield patterns identical with that of pseudobrookite (B.M. 74455) from Arany, Transylvania, the probable reaction being 2FeTiO3 + O→Fe2TiO3; TiO2; no lines due to rutfle, anatase, or brookite in addition to those of pseudobrookite, have, however, been detected on powder photographs of oxidized flmenite.

Page 111 note 1 Bunn, C. W., Chemical crystallography, Oxford, 1945, p. 132. [M.A. 9 217.]Google Scholar

Page 112 note 1 T. Crook, Min. Mag., 1910, vol. 15, p. 281; L. g. Spencer, tom. cir., p. 431.