Hypersthene is a mineral with a hardness of 6 out of 10 on the Mohs scale of mineral hardness [?]. These Orthorhombicly structured gems are made of iron magnesium silicate, their full chemical compound being (Fe,Mg)SiO3.
Hypersthene is an important iron-rich orthopyroxene in the Pyroxene group with an orthorhombic crystal system. Other orthopyroxenes forming a complete chemical series with hypersthene are enstatite and bronzite. When the iron content of enstatite increases than it is converted into hypersthene, therefore it is opaque. Pyroxenes are a widespread group of rock-forming silicates.
Hypersthene occurs as richly-faceted crystals, columnar, or tabular, in mostly-massive, granular-laminated aggregates which are usually green-black, black-brown or reddish.
It has imperfect cleavage, an uneven to brittle fracture, with a submetallic luster, and partly copper-red iridescence. It is fusible and may display a play of color in natural light, called "schillerization."
It contains up to 1:1 ratio of magnesium and iron, with bronzite being the intermediate form between enstatite and hypersthene.
It occurs mostly as common constituents of basic and ultrabasic igneous rocks easily seen in gabbros and pyroxenites, in some andesites and stony meteorites, in some thermally metamorphosed shales and high-grade regionally metamorphosed rocks.
Deposits are found in Massif Central (France), Baikal area (Russia), Labrador (Canada), New York, Adirondack, Colorado (USA),
Related occurrences of hypersthene include eastenite - a green variety of chrome enstatite-hypersthene; ferrosilite - same as iron- hypersthene; hornblende labrador - hypersthene with labradorite effects, an optical effect of change of multi-vivid colors suggestive of the Northern lights; hypersthenite - a coarse-grained igneous rock, which is composed mainly of hypersthene; paulite - blackish hypersthene contains coppery-colored inclusions, from St. Paul Island, Canada.
Hypersthene takes its name from the Greek meaning "over strength," in reference to its greater hardness than hornblende, which hypersthene is often confused for.
Hypersthene is prized by collectors and sometimes faceted into gemstones. As it sometimes has a metallic or bronzy luster, it can be cut cabochon with cats-eye effect.