noun.
A dark-green to black pyroxene mineral, (Ca,Na)(Mg,Fe,Al)(Si,Al)2O6, that contains large amounts of aluminum, iron, and magnesium.
The Century Dictionary and Cyclopedia
noun.
The name of this member of the pyroxene group of silicate minerals is frequently used in petrography in composition with the name of any rock in which it occurs as a prominent or noteworthy constituent: as, augite-andesite, augite-syenite, augite-gneiss, etc.
noun.
The dark-green to black variety of pyroxene characteristic of basic eruptive rocks like basalt.
the GNU version of the Collaborative International Dictionary of English
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.