Kyanite!

KYANITE

the name derived from the greek word kyanos, meaning blue. it is typicaly blue siliacte mineral, comonly found in aluminium-rich metamorphic pegmatites & sedimentary rocks. it is strongly anisotrophic , in that its hardness varies depending on its crystallographic direction. this is used primarily in refractory & ceramic products, including porcelain plumbing fixtures & dinnerware. it is also used in electrical insulators & abrasives. it undergoea an irreverssible expansion when fired at high temperature. this is also been used as gemstone.

ASSOCIATED MINERALS OF KYANITE :
andalusite Ai2SiO5
sillimanite Al2SiO5
Quertz SiO2
staurolite Fe2Al9Si4Onn(OH)2
micas AB2-3(X1Si)4 O10(O, F, OH)2
garnete A3B2(SiO4)3