Ngulube Kimberlite, Mphoengs
Grid Ref (WGS84 Lat/Long in decimal degrees)
The Ngulube kimberlite was discovered in 1998 by aeromagnetic survey by Debeers Zimbabwe. It is intruded into the Zimbabwean Archean craton a few kilometres from the Botswana border. Surface exposure of the kimberlite is poor, however, the central parts are presently exposed by trenching and shafts. Its mineralogy is typical of Group I kimberlites including abundant macrocrysts of olivine, picroilmenite, Cr-diopside, pyrope garnet; phenocrysts of olivine and microphenocrysts of spinel. Notably phlogopite is present though not abundant. Tuffisitic diatreme facies rocks are dominant with some evidence of crater facies material. Abundant xenoliths of lower and upper crustal wallrocks also occur in the kimberlite. These xenoliths are felsic in composition and derived from the gneissic Archean basement. The Ngulube kimberlite is of no economic significance with grades only going up to 3CPHT.