Occurrence of wagnerite in Mg–Al granulites of Sonapahar, Meghalaya

Abstract

We report for the first time the occurrence of rare phosphate wagnerite as a stable phase from the Mg-Al granulites of Sonapahar. The wagnerite bearing assemblages consist of the spinel, phlogopite, brucite and corundum. The wagnerite appears in the Mg-Al granulites due to the breakdown of spinel and fluorapatite. The mineral chemistry of the phases has been discussed from the EPMA data, which reveals that the fluorine content of the wagnerite is relatively low due to the exchange of F to coexisting phases. The major oxide analysis of the rocks show the low content of Ca, which is the requisite for the occurrences of wagnerite.