Associated minerals in eclogites include garnet, quartz or coesite, rutile, kyanite, phengite, and lawsonite. Typical associated minerals include&colon; kyanite, andalusite, topaz, mica and quartz. These minerals, known as index minerals, include sillimanite, kyanite, staurolite, andalusite, and some garnet. Major minerals found here include coal, iron ore, asbestos, chromite, mica, and kyanite. Kyanite in metamorphic rocks generally indicates pressures higher than four kilobars. Andalusite, kyanite, and sillimanite are naturally occurring aluminosilicate minerals that have the composition AlSiO. It has the characteristic mineral assemblage of kyanite + talc, responsible for its white colour. Sillimanite is one of three aluminosilicate polymorphs, the other two being andalusite and kyanite. It is a group of metamorphic minerals - sillimanite, kyanite and andalusite. By metamorphic isograd, the Main Central Thrust follows the kyanite isograd. Under this criterion, crystals of kyanite appear upward of several meters from the lithologic change. Color varieties include recently discovered orange kyanite from Tanzania. Andalusite is trimorphic with kyanite and sillimanite, being the lower pressure mid temperature polymorph. Kyanite is strongly anisotropic, in that its hardness varies depending on its crystallographic direction. Kyanite is used primarily in refractory and ceramic products, including porcelain plumbing and dishware.