The mineral occurs as exsolution lamellae and particles in rutile, coexisting with kyanite, sillimanite, and tourmaline in a highly metamorphosed gneiss.
22.
Andalusite is stable at low pressure, kyanite is stable at high pressure but relatively low temperature and sillimanite is stable at high temperature.
23.
Over the years, diamonds have yielded blemishes of eclogite and kyanite, metamorphic rocks thought to have been formed at great depths and heats.
24.
The aluminosilicates are a group of three minerals kyanite, andalusite, and sillimanite which share the chemical formula Al 2 SiO 5.
25.
With increasing temperature and pressure garnet appears, and then kyanite ( at relatively high pressure ) or sillimanite ( at relatively high temperature ).
26.
Besides coal, resources such as slate, kyanite, sand, and gravel are mined, with an annual value over $ 2 billion.
27.
Therefore, kyanite is often the preferred material, as it contributes both mechanical strength and, in amounts up to 20 %, significantly reduces thermal expansion.
28.
Felsic rocks in these terranes contain sillimanite, kyanite, coesite, orthoclase and pyroxene, and are rare, peculiar rocks formed by an unusual tectonic event.
29.
The High Himalayan Crystalline units ( HHC ) are mainly composed of kyanite-to sillimanite-grade gneisses intruded by High Himalayan leucogranites at structurally higher levels.
30.
Kyanite has been used as a semiprecious gemstone, which may display cat's eye chatoyancy, though this use is limited by its anisotropism and perfect cleavage.
