Monoclinic

Monoclinic

Spodumene is a comparatively rare mineral found almost exclusively in lithium-rich pegmatites. It is worked as an ore of lithium but is it most highly prized as a gem mineral. Discovered in 1800, it was named after the Greek spodumenos reduced to ashes, alluding to the grayish-white mass that is formed when the mineral is ignited.

Discovered in 1888 in Yemen, this mineral was named for Emil Riebeck (1853-1885), a German explorer, ethnologist, and mineralogist. The asbestiform variety occurs in South Africa in metamorphosed ironstone and is mined on a large scale.

Also known as "jade," this mineral was first discovered in 1863. It occurs in large masses formed by metamorphism. It has long been highly prized in the Far East where it is worked into ornaments and utensils of great variety and beauty.

This is an important and widely distributed rock-forming mineral, occurring in both igneous and metamorphic rocks. Its name comes from an old German word meaning "horn" and "blind" or "to deceive," in illusion to it occurring in ore deposits but not yielding any metal. It can be distinguished from augite by its cleavage angles.

A member of the pyroxene group of minerals, this mineral occurs in metamorphosed iron formations and as xenoliths in kimberlite. It was named after M.A. Ludwig Hedenbers, a Swedish chemist, who first described the species.

Found only in metamorphic rocks such as schist, eclogite, and marble, this mineral was first discovered in 1845 in Greece. It is named from the Greek word for "sky-blue" and "to appear," in allusion to its color. A variety of this mineral is widely used for jewelry under the name of tiger’s eye.

One of the most common members of the pyroxene group of minerals, diopside is named from the Greek word for "double" and "appearance," in allusion to two possible orientations of the prism zone. It is characteristically found as a contact metamorphic mineral in limestone and dolomites. Transparent varieties can be cut and used as gemstones.

One of the rock-forming minerals, augite was named by Abraham G. Werner in 1792 from the Greek word for "shine" or "luster," in allusion to the appearance of its cleavage surfaces. It is a member of the pyroxene group of minerals and can be distinguished from hornblende by its cleavage angles.

Characterized by its peculiar green color and one perfect cleavage, this mineral was discovered in 1801 in France. It forms during the metamorphism of an impure limestone and is especially characteristic of contact metamorphic deposits in limestone. The name comes from the Greek word meaning "increase," in allusion to the crystal characteristic of one longer side at the base of the prism.

Formed during metamorphism of aluminum-rich rocks, this mineral commonly occurs as twined crystals earning it the name "fairy crosses". Its name is derived from the Greek word meaning "cross," in allusion to its cruciform twins.