Chrome-spinels from the Massif du Sud, southern New Caledonia

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Abstract
Summary: Approximately forty, variously shaped, chromitite bodies occur in dunites and harzburgites of the alpine-type peridotite complex of southern New Caledonia. The chromitites consist of pichrochromite (59 to 42% Cr2O3) and serpentinized olivine (Fo96-92) and display a variety of textures (massive, disseminated, and orbicular) consistent with a magmatic cumulate origin. Dunites contain olivine (Fo93−97) and 1 to 3% picrochromite (50 to 39% Cr2O3). Harzburgites have less than 1% spinel, ranging from picrochromite to ceylonite (45 to 28% Cr2O3) and often forming symplectic intergrowths with bronzite. Temperatures of crystallization of the cumulate picrochromites are believed to have been about 1200 °C while the more aluminous symplectic spinels equilibrated under different conditions and may reflect a late stage recrystallization episode.