How do I identify Osumilite?

Osumilite can be identified by its hardness of 5 - 6 on the Mohs scale, Blue color. Look for these key characteristics when examining specimens.

What color is Osumilite?

Osumilite typically appears in Blue. Color can vary depending on impurities and formation conditions.

How hard is Osumilite?

Osumilite has a hardness of 5 - 6 on the Mohs scale. This gives it moderate hardness.

Osumilite

A variety of Minerals

What is Osumilite?

Osumilite is a very rare potassium-sodium-iron-magnesium-aluminium silicate mineral. Osumilite is part of the milarite group (also known as the milarite-osumilite group) of cyclosilicates.

Osumilite Market Value Calculator

Estimate the market value of Osumilite using size, quality, and finish. This preview calculator is for quick context and is not a formal appraisal.

Osumilite Localities Map

See where Osumilite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

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North ZoneCentral RidgeSouth Basin

Key Characteristics

Characteristics of Osumilite

Osumilite chemical formula is (K,Na)(Fe,Mg)2(Al,Fe)3(Si,Al)12O30. It is translucent and the typical coloring is either blue, black, brown, or gray. It displays no cleavage and has a vitreous luster. Osumilite has a hardness between 5-6 on the Mohs hardness scale. The hexagonal crystal structure of osumilite is an unusual molecular make-up. The primary unit is a double ring, with a formula of Si12O30. Normal cyclosilicate have rings composed of six silicate tetrahedrons; Si6O18. In a double ring structure, two normal rings are linked by sharing six oxygens, one from each tetrahedron in each six membered ring.

Formation of Osumilite

Osumilite, was first discovered as grains in volcanic rocks near Osumi, Japan. It was confused with a similar mineral cordierite because of their similar coloring. It can be found in high-grade metamorphic rocks, xenoliths and in the groundmass of rhyolite and dacite. Osumilite is found in the Obsidian Cliffs, Oregon; Sardinia, Italy; Kagoshima and Yamanashi Prefecture, Japan; and the Eifel district in Germany. Osumulite pseudomorphs are known from a number of ultrahigh-temperature rocks, including those of southern Madagascar