Uvarovite from chromite-bearing ultramafic intrusives, Orissa, India, a crystal-chemical characterization using 57Fe Mossbauer spectroscopy

摘要

EPMA analyses of uvarovite from the chromite-bearing ultramafic intrusive of Sukinda, India, show that uvarovite containing 9.83 to 17.68 wt% Cr₂O₃ represents a solid solution of the binary uvarovite-andradite series with Uva_34–58 And_42–58 Associated chromite grains with 57–59 wt% Cr₂O₃ do not show any compositional variation from core to rim. 57Fe Mössbauer spectroscopic studies on the uvarovite samples undertaken both at room temperature (298 K) and low temperature (110 K) indicate the presence of Fe3+ only in octahedral coordination. Uvarovite grew from chromite (Cr source) and pyroxenes (Al, Fe, and Ca source) of the ultramafic host rocks.