Kyanite from Brazil

Kyanite, whose name derives from the Greek word kyanos, meaning blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite is a diagnostic mineral of the Blueschist Facies of metamorphic rocks.

Kyanite is a member of the aluminosilicate series, which includes the polymorph andalusite and the polymorph sillimanite. Kyanite is strongly anisotropic, in that its hardness varies depending on its crystallographic direction. While this is a feature of almost all minerals, in kyanite this anisotropism can be considered an identifying characteristic.

Uses of kyanite

Kyanite is used primarily in refractory and ceramic products, including porcelain plumbing fixtures and dinnerware. It is also used in electrical insulators and abrasives. An interesting property of kyanite is that it undergoes an irreversible expansion when fired at high temperature. Kyanite has also been used as a gemstone, though this use is limited by its anisotropism and perfect cleavage. Kyanite is one of the index minerals that are used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism. Finally, as with most minerals, kyanite is a collector's mineral.

Associated minerals

Kyanite is usually found in association with its polymorphs, as well as other silicate minerals. These include:

• andalusite, Al₂SiO₅
• sillimanite, Al₂SiO₅
• quartz, SiO₂
• staurolite, Fe₂Al₉Si₄O₂₂(OH)₂
• micas, AB_2-3(X, Si)₄O₁₀(O,F,OH)₂
• garnets, A₃B₂(SiO₄)₃

Alternative names

Kyanite has several alternative names, including disthene, munkrudite and cyanite. White-grey kyanite is also called rhaeticite.

Notes for identification

In Buckingham County, Virginia kyanite from the mine at Mt. Willis is transported by train on the Buckingham Branch Railroad.

References

• WebMineral Listing
• MinDat Listing
• Mineral Galleries

de:Kyanit et:Küaniit es:Cianita eo:Kianito eu:Zianita hr:Kianit it:Cianite he:?????? hu:Kianit nl:Kyaniet ja:??? pl:Dysten pt:Cianite ru:?????? sk:Kyanit fi:Kyaniitti sv:Kyanit