Noun
A variety of pyroxene, usually of a black or dark green color, occurring in igneous rocks, such as basalt; -- also used instead of the general term pyroxene.
Source: Webster's dictionaryGood crystals of augite and olivine are also to be obtained in the ash beds of Vesuvius and of many other volcanoes, ancient and modern. Source: Internet
In rhyolites and trachytes, early crystals of hornblende and biotite may be found in great numbers partially converted into augite and magnetite. Source: Internet