Chromite in Komatiites, II. Modification during Greenschist to Mid-Amphibolite

Chromite compositions in komatiites are influenced by metamorphic chromite is highly susceptible to modification during processes, particularly above 500°C. Metamorphosed chromite is early hydrous alteration and subsequent prograde meta-substantially more iron rich than igneous precursors, as a result of morphism of host rocks. This modification is the subject Mg–Fe exchange with silicates and carbonates. Chromite meta- of this paper. morphosed to amphibolite facies is enriched in Zn and Fe, and Metamorphic modification of chromite has been dis-depleted in Ni, relative to lower metamorphic grades. Relative cussed extensively in the literature in the context mainly of proportions of the trivalent ions Cr3+, Al3+ and Fe3+ are not ophiolitic or ‘alpine ultramafic ’ complexes (Onyeagocha