Igneous rocks are named and classified based on their texture and mineral make-up. The color index for igneous rock can provide an estimate of mineral composition by measuring the proportion of dark and light mineral components in a specimen.

Augite is a dark mineral important in the formation of igneous rocks that is most frequently found in basalts, dolerites, and gabbros. Often prismatic in shape, augite may consist of rectangular or octagonal cross sections and is typically dark green to black in color. Although its name derives from the Greek word for brightness, augite is not usually considered attractive and is generally only of interest to collectors and scientists.

The Mohs scale is commonly utilized to express the hardness of minerals. On this scale, a comparison is made of ten conventional minerals that are arranged in order from the softest, talc, to the hardest, diamond. Augite falls in the middle range, exhibiting a relative hardness between five and six, which indicates that it can scratch apatite, number five on the Mohs scale, but is itself scratched by orthoclase, which ranks sixth.