Synopsis: The rocks of the southern half of the Morven-Cabrach mass consist mainly of norites, with two northerly dipping layers of ore- and olivine-rich ferrogabbro. In the north there is a progression of rocks from hypersthene-gabbro through quartz-biotite-norite to xenolithic quartz-mica-diorite. All the rocks are relatively iron-rich, and no highly magnesian types are found. Mineral compositions are remarkably constant, and chemical variation is slight. The mass has been intruded in its present position and is a (relatively) narrow, steep-sided, dyke-like body. A tentative hypothesis, based largely on the dimensions of the mass and the high temperatures of the country rocks, is put forward for the lack of cryptic variation. The relationships between the Morven-Cabrach mass and the postulated north-east basic sheet are considered, and a feeder-pipe role is suggested for Morven-Cabrach.