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Published August 1984 | public
Journal Article

Gamagarite: a re-examination and comparison with brackebuschite-like minerals

Abstract

Gamagarite from Postmasburg district, Cape Province, Republic of South Africa, is reexamined using analytical chemical, infrared spectra, and X-ray diffraction techniques. The data indicate that gamagarite is isostructural with brackebuschite; space group is P2_1/m (assumed center of symmetry) with unit cell constants ɑ = 9.15(1), b = 6.17(1), c = 7.88(l)Å, β = 112.7(2)°. Infrared spectra indicate that strongly hydrogen-bonded OH^- is the dominant hydrogen-bearing species in both gamagarite and brackebuschite. Consequently, with a reevaluation of previously published structure data, our interpretation prefers the brackebuschite-type structure as a partially acid vanadate (arsenate and phosphate) containing HVO^(2-)_4 -type units rather than as a hydrated vanadate containing structural water, as previously described. However, there are uncertainties with the assignment of Mn oxidation state.

Additional Information

© 1984 Mineralogical Society of America. Manuscript received, May 21. 1982; accepted for publication, February 21. 1984. Discussions with Dr. Eric Dowty were helpful to G.E.H. Infrared studies were supported in part by NSF grant EAR 79-19987.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023