Statistical Classification of Garnets from Kimberlite and Associated Xenoliths

Cluster analysis of 352 garnets from kimberlites, associated xenoliths, and diamonds has allowed recognition of 12 chemically coherent groups, on the basis of TiO₂, Cr₂O₃, FeO, MgO, and CaO contents. A flow-sheet classification scheme was created for classification of new garnets from kimberlites. Other points discussed are: correlation between the various oxides (including MgO-FeO correlations and their meaning); the chemistry of garnets from deformed Iherzolites; and the recognition of one group of garnets that probably crystallized from the kimberlite magma, as opposed to most other kimberlite garnets which are chemically the same as those occurring in xenoliths.