Chlorite is a common green mineral group belonging to the phyllosilicate (sheet silicate) family. It is especially abundant in metamorphic rocks and forms during the alteration of other ferromagnesian minerals such as biotite, pyroxene, amphibole, and garnet. Chlorite...
Augite is one of the most common minerals in the pyroxene group and an important rock-forming mineral in igneous and metamorphic rocks. It is typically dark green, dark brown, or black and is especially abundant in basalt, gabbro, and other mafic rocks. Because augite...
Hornblende is the most common member of the amphibole mineral group and one of the most important rock-forming minerals in geology. It is typically dark green to black and is commonly found in igneous and metamorphic rocks. Hornblende is important because it: forms in...
Biotite is a common dark-colored mica mineral found in a wide variety of igneous and metamorphic rocks. It is easily recognized by its black to dark brown color, sheet-like structure, and perfect basal cleavage. As a member of the mica group, biotite splits into thin...
Muscovite is the most common mineral in the mica group and is easily recognized by its thin, transparent sheets and perfect cleavage. It is a potassium-rich aluminum silicate mineral that occurs in a wide variety of igneous, metamorphic, and sedimentary rocks. Because...
