The Ianapera emerald deposit (South Madagascar) formed by metasomatism along the contact of migmatitic gneiss and lenses of serpentinite and amphibolite, initiated by shearing related to a Pan-African tectono-metamorphic event. We report the results of fluid inclusion studies on Ianapera emerald employing microthermometry, Raman spectrometry, and electron microprobe and SEM analysis. Several types of inclusions are present within the same primary inclusion population: (1) aqueous-rich inclusions containing daughter carbonate phases and NaCl-HCO3− solution, commonly with a salinity of ∼7 wt% NaCl equiv.; (2) CO2 ± CH4 inclusions mostly of high density (about 1 g/cm3) which usually contain several daughter carbonate phases; (3) multi-aggregate solid inclusions composed of hydrocarbon-sulfur-carbonate aggregates; and (4) oil-inclusions. The conditions of emerald growth determined on the basis of fluid inclusion characteristics and a petrogenetic grid are T = 630-710°C and P = 5.0-5.8 kbars. The Ianapera emerald is unique with regard to its chemical composition, fluid inclusion content, and high P-T conditions of growth.
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