Mineral description : Kyanite

Kyanite from Stora Akersvatnet, Norway.

Kyanite are created in the temperature- pressure area at all pressures above 0 at 250 degrees C to pressures above 9 kbar at 750 degrees C.
As a rarity sometime clear crystals of kyanite is used in jewellery, both as cabochones and facetted stones.

Chemical formula	Al2SiO5
Hardness	4-5 along the cleavage plane and 6-7 across.
Density	3.67
Color	Light blue.
Crystal form	Triclinic. Forms long bladed crystals or radially aggregates.
Luster	glas.
Description
Optical properties	Weak pleocroism.
Habitat	Appears only in highly metamorphic rocks, never in eruptive rocks. The crystals grows in quartz jugs that lies in the dark metamorphic schist.
Associates	Often with staurolite in the schist. Sometimes with beryl and rutil in the quartz jugs.
Notes	Looks like topas, but topas occurs in pegmatites, where kyanite never exists. Polymorphs : Andalusite and Sillimanite
Locations	In quartz jugs at Hegset in the Nea valley, Norway. Kyanite are mined at Horrsjöberg, Värmland (together with lazulite, pyrophyllit, and brown rutil). Västanå, Skåne ( with lazulite ). Dicksberget Värmland.

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