Hypersthene is a common rock-forming inosilicate

Silicate minerals

The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...

 mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 belonging to the group of orthorhombic pyroxene

Pyroxene

The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems...

s. Many references have formally abandoned this term, preferring to categorise this mineral as enstatite or ferrosilite

Enstatite

Enstatite is the magnesium endmember of the pyroxene silicate mineral series enstatite - ferrosilite . The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks...

. It is found in igneous

Igneous rock

Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...

 and some metamorphic rock

Metamorphic rock

Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

s as well as in stony and iron meteorite

Meteorite

A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

s. It forms a solid solution series with the minerals enstatite and ferrosilite, being a mid-way member between the two. Pure enstatite contains no iron, while pure ferrosillite contains no magnesium; hypersthene is the name given to the mineral when a significant amount of both elements are present. The chemical formula is (Mg,Fe)SiO₃.

Distinctly developed crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

s are rare, the mineral being usually found as foliated masses embedded in the igneous rocks norite

Norite

Norite is a mafic intrusive igneous rock composed largely of the calcium-rich plagioclase labradorite and hypersthene with olivine. Norite is essentially indistinguishable from gabbro without thin section study under the petrographic microscope...

 and hypersthene-andesite

Andesite

Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...

, of which it forms an essential constituent. The coarse-grained labradorite

Labradorite

Labradorite , a feldspar mineral, is an intermediate to calcic member of the plagioclase series. It is usually defined as having "%An" between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573....

-hypersthene-rock (norite) of the island of Paul off the coast of Labrador

Labrador

Labrador is the distinct, northerly region of the Canadian province of Newfoundland and Labrador. It comprises the mainland portion of the province, separated from the island of Newfoundland by the Strait of Belle Isle...

 has furnished the most typical material; and for this reason the mineral has been known as Labrador hornblende

Hornblende

Hornblende is a complex inosilicate series of minerals .It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....

 or paulite.

Color is often gray, brown, or green, and the luster

Lustre (mineralogy)

Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....

 is usually vitreous to pearly. The pleochroism

Pleochroism

Pleochroism is an optical phenomenon in which a substance appears to be different colors when observed at different angles with polarized light.- Background :Anisotropic crystals will have optical properties that vary with the direction of light...

 is strong, the hardness is 5–6, and the specific gravity

Specific gravity

Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 is 3.4–3.9. On certain surfaces it displays a brilliant copper-red metallic sheen, or schiller, which has the same origin as the bronzy sheen of bronzite

Bronzite

Bronzite is a member of the orthopyroxene group of minerals, belonging with enstatite and hypersthene to the orthorhombic series of the group...

, but is even more pronounced. Like bronzite, it is sometimes cut and polished as a gemstone

Gemstone

A gemstone or gem is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments...

.

The name hypersthene comes from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 and means "over strength". It is in allusion to its greater hardness than the amphibole

Amphibole

Amphibole is the name of an important group of generally dark-colored rock-forming inosilicate minerals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures.-Mineralogy:...

 mineral hornblende

Hornblende

Hornblende is a complex inosilicate series of minerals .It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....

, a mineral with which it is often confused.