Green augite and hypersthene form a considerable part of these rocks, they may contain also biotite, hornblende and quartz.
hypersthene (or bronzite) is characteristic of another group.
hypersthene, when present, is often strikingly pleochroic in colours varying from pink to bright green.
Some contain biotite, others augite or hypersthene; many have a small amount of quartz.
hypersthene is not the prevailing pyroxene, and olivine is usually present, often in such abundance as to make the rock a basalt.
Both are light colored, and the pleochroism of the hypersthene is sometimes quite faint.
It may be noted also that hypersthene shows a tendency to magmatic alteration, although only rarely.
On Crater Peak, and below on Gibraltar, hypersthene andesite occurs with considerable variation of color and texture.
hypersthene and scapolite both may occur in these rocks and they are sometimes garnetiferous.