Mineral description : Sillimanite

Sillimanite from Stakholmen. Sillimanite from Kölaberget.

Chemical formula Al₂SiO₅

Hardness 6-7

Density 3.2

Color Grey, brown to light green.

Crystal form Ortorombic. Long and thin crystals.

Luster Glas or silk.

Description .

Habitat Quite common in Sweden, as a ingredience in granites and gneiss. Larger aggregates are not so common. Also at the borderzones of pegmatites.

Associates .

Notes All three disten minerals are used to high temperature cheramics as in sparkplugs.
Polymorphs : Kyanite and Andalusite
Sillimanite is created at temperatures higher than 550 degrees C and in all pressures.

Locations

Kolsva feldspar mine, at the borderzone of the pegmatite. In yellow fibric aggregates together with garnet and biotite.
Långfallsgruvan Grangärde in Dalarna.
Malmberget in Norrbotten.
Stakholmen, Hassela.
Kölaberget, North of Hälsingland.

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axelsson@acc.umu.se

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Last changed : 1998-03-07

Chemical formula	Al₂SiO₅
Hardness	6-7
Density	3.2
Color	Grey, brown to light green.
Crystal form	Ortorombic. Long and thin crystals.
Luster	Glas or silk.
Description	.
Habitat	Quite common in Sweden, as a ingredience in granites and gneiss. Larger aggregates are not so common. Also at the borderzones of pegmatites.
Associates	.
Notes	All three disten minerals are used to high temperature cheramics as in sparkplugs. Polymorphs : Kyanite and Andalusite Sillimanite is created at temperatures higher than 550 degrees C and in all pressures.
Locations	Kolsva feldspar mine, at the borderzone of the pegmatite. In yellow fibric aggregates together with garnet and biotite. Långfallsgruvan Grangärde in Dalarna. Malmberget in Norrbotten. Stakholmen, Hassela. Kölaberget, North of Hälsingland.