Kyanite (redirected from kyanitic)

kyanite

 or cyanite or disthene

Silicate mineral, one of several phases in the aluminum silicate (Al₂SiO₅) system. Its colour ranges from gray-green to black or blue, with blue and blue-gray being most common. It occurs in Switzerland, Italy, the Ural Mountains, and New England (U.S.). Kyanite is a raw material in the manufacture of spark plugs. A clear, deep-blue variety is sometimes cut as a gemstone.

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kyanite [′kī·ə‚nīt]

(mineralogy)

Al₂SiO₅A blue or light-green neosilicate mineral; crystallizes in the triclinic system, and luster is vitreous to pearly; occurs in long, thin bladed crystals and crystalline aggregates. Also known as cyanite; disthene; sappare.

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Kyanite 

(also called disthene), a silicate mineral with the chemical composition Al₂[SiO₄]O. Kyanite contains up to 63.1 percent Al₂O₃ and sometimes up to 2 percent admixtures of iron oxide or chromium oxide. It crystallizes in the triclinic system, forming long columnar or tabular crystals and their aggregates. Its color ranges from greenish blue to dark blue-green and yellow; sometimes it is colorless. The mineral is characterized by a sharp anisotrophy in hardness. In the direction parallel to the length of the crystal the hardness equals 4.5, and in the direction at right angles, it is up to 7.5. The density ranges from 3,560 to 3,680 kg/m³. Kyanite is formed with the plutonic metamorphism of clay-rich sedimentary rocks; it is also encountered in quartz veins and contact zones of pegmatites. It is used as a valuable high-alumina raw material for refractory and acidresistant articles and for spark plug insulators for internal combustion engines.