Summary: Microprobe analysis of leached and unleached varieties of a charnockitic rock from Madras supports the contention of Howie (1964) that the characteristic dark greenish colour of such rocks is contained mainly in fine (chloritic ?) veinlets cutting the feldspar and quartz, though a certain amount appears to be contained in exsolved sodium feldspar. Leaching of the darkish colour of the charnockitic rock has not affected the crystallographic state of the potassium feldspar.