The name of a group of minerals, usually of a green color and micaceous to granular in structure. They are hydrous silicates of alumina, iron, and magnesia.
Any of a group of hydrated silicates containing aluminum and iron. Green in color. Derived from augite, hornblende, or biotite. Resembles mica in appearance but the flakes are not as elastic.
A group of platy, monoclinic, usually greenish minerals. They are widely distributed in low grade metamorphic rocks. Associated with and resemble the micas.