Abstract
The assemblage tephroite-hausmannitess-galaxitess has been found in a granulite-facies manganese ore body associated with metabasites and quartzrich lithologies. The metamorphic rocks are located in the Khawr Fakkan massif near the northern end of the Semail Ophiolite, United Arab Emirates (U.A.E.), metamorphosed at 800–850°C and 6.5–9 kbar. The galaxite shows approximately 35% solid solution of hausmannite, similar to that reported for jacobsite and franklinite whereas the solid solution of galaxite in hausmannite is maximally 7%. The assemblage of tephroite-hausmannite and hausmannite-galaxite indicates a restricted log fO2 of-9 to-11 which is outside the stability of braunite under similar physico-chemical conditions. The modal abundance of the minerals and bulk rock chemistry indicate that the present assemblage was formed from the breakdown of Fe-poor braunitess+hausmannitess.
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Gnos, E., Peters, T. Tephroite-hausmannite-galaxite from a granulite-facies manganese rock of the United Arab Emirates. Contr. Mineral. and Petrol. 120, 372–377 (1995). https://doi.org/10.1007/BF00306514
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DOI: https://doi.org/10.1007/BF00306514