MICROCRYSTALLINE CHROME SPINELLIDS IN KIMBERLITE AND ALKALIC ULTRAMAFIC ROCKS

Abstract

This article presents and discusses the results of analyses of microcrystalline chrome spinellids from rocks of the alkalic ultramafic series in the Maymecha-Kotuy and the Karelia-Kola regions and from kimberlites, chiefly from the northern fields of Siberia. These chrome spinellids were analyzed with the Camebax electron microprobe, using the energy-dispersion spectrometer attachment and the ZAF program to calculate element concentrations. Their FeO and Fe2O3 content was determined by calculation from the crystallochemical formula. Over 200 analyses were done. Study results are discussed.