The unaltered tholeiite of Kinkell quarry, Stirlingshire, has been reinvestigated and the mineral constituents have been separated and analysed both chemically and spectrographically. No anomalies were found and the distribution of the trace elements in the rock is normal. The two main mineral constituents of the rock—augite and labradorite—had the same crystallization ranges and maintained approximately equal rates of crystallization until the rock was 70 % crystalline.