charnockite A light-coloured, medium to coarse-grained igneous rock containing quartz and microcline feldspar (see ALKALI FELDSPAR) as major components with, in order of decreasing abundance, oligoclase feldspar (see PLAGIOCLASE FELDSPAR), hypersthene, biotite, and magnetite.Despite its low abundance, hypersthene (a calcium-poor, iron-rich …