Photo of Hypersthene in Processed & Rough Form
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.
What causes Hypersthene's metallic sheen?
The distinctive bronze to copper-colored schiller effect comes from oriented platelet inclusions within the crystal structure. This metallic flash is most visible when the stone is properly oriented and cut as a cabochon.
Why is it also called Velvet Obsidian?
Some varieties of hypersthene show a velvety appearance due to fine inclusions, leading to the trade name "Velvet Obsidian" despite not being obsidian at all. This marketing term can be misleading as it's actually a distinct mineral species.
Are green Hypersthenes natural?
Yes, while most hypersthene appears black or dark brown, some specimens show attractive green hues, particularly from Indian sources. The green variety with strong schiller is highly sought after.
What makes Mexican Hypersthene unique?
Mexican hypersthene is known for exceptionally strong bronze schiller and often larger sizes. These specimens frequently show more dramatic play of light than material from other locations.
How can I tell genuine Hypersthene from similar stones?
Look for distinctive schiller effect, hardness of 5-6, and two directions of cleavage. The bronze flash should appear internal rather than surface-like. Similar-looking black stones rarely show the same metallic sheen.
Why do some pieces show different colored flashes?
Multiple color flashes can occur due to varying orientation of inclusion platelets. The best specimens show strong copper-bronze flash, but some may display silver, gold, or multicolored effects.
Is Cat's Eye Hypersthene real?
While rare, chatoyant hypersthene does exist. These specimens show both cat's eye effect and schiller, creating a unique optical phenomenon. Most come from India and South Africa.
The specific gravity [?] for Hypersthene is 3.35, its refractive index [?] is 1.65-1.67, and its double refraction [?] is 0.01.
History
Hypersthene takes its name from the Greek meaning "over strength," in reference to its greater hardness than hornblende, which hypersthene is often confused for.
Industrial Usages
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.
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