Tremolite is found most frequently in metamorphosed dolomitic limestone. It was named by J.G.A. Hopfner for the Tremola Valley, Switzerland. A felted aggregate of tremolite fibers goes under the name of “mountain leather” or “mountain cork.” The mineral frequently is fibrous and is the material to which the name “asbestos” was originally given.

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 a mineral that is part of the enstatite-ferrosilite series and is commonly regarded as a mid-way member between these two end members. It occurs in mafic igneous rocks and is named from two Greek words meaning “very” and “strong” because ( ) its hardness is greater than that of hornblende.

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.

This mineral is usually recognized by its color, cleavage, and unusual luster. It commonly occurs in magic igneous rocks and was named from the Greek word meaning “opponent” because of its refractory nature.

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.