Mineral description : Gadolinite

Gadolinite from Ytterby.

Mineral class Silicates : Cyclosilicates : Beryl - Tourmaline group

Chemical formula Y₂FeBe₂(Si₂O₁₀)

Crystal system Monoclinic.

Habitus Rounded coarse prismatic crystals or grainy masses.

Cleavage No cleavage.

Hardness 6.5-7

Density 4.0-4.5

Color Black, opaque, but traces from uranium and thorium often gives it a rust colored surface.

Streak Greenish to grayish green.

Luster Greasy.

Description

Occurance Most commonly in pegmatites.

Associates

Named after the finnish chemist Johan Gadolin (1760 - 1852).
Working in Uppsala, Sweden, in 1794 he analysed a black mineral from Ytterby and discovered an unknown metal. The metal was named Yttrium after Ytterby and the black mineral was named gadolinite in his honor.

Locations A rare mineral with a few localities in Sweden.

Ytterby feldspar quarry, Stockholm archipelago.
Kårarvet and Finnbo, Falun.
Åskagen pegmatite, Värmland.
Kolsva feldspar mine, Västmanland.
Routavaara quartz quarry, Jokkmokk.

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Last changed : 1998-07-06

Mineral class	Silicates : Cyclosilicates : Beryl - Tourmaline group
Chemical formula	Y₂FeBe₂(Si₂O₁₀)
Crystal system	Monoclinic.
Habitus	Rounded coarse prismatic crystals or grainy masses.
Cleavage	No cleavage.
Hardness	6.5-7
Density	4.0-4.5
Color	Black, opaque, but traces from uranium and thorium often gives it a rust colored surface.
Streak	Greenish to grayish green.
Luster	Greasy.
Description
Occurance	Most commonly in pegmatites.
Associates
Named after the finnish chemist Johan Gadolin (1760 - 1852). Working in Uppsala, Sweden, in 1794 he analysed a black mineral from Ytterby and discovered an unknown metal. The metal was named Yttrium after Ytterby and the black mineral was named gadolinite in his honor.
Locations	A rare mineral with a few localities in Sweden. Ytterby feldspar quarry, Stockholm archipelago. Kårarvet and Finnbo, Falun. Åskagen pegmatite, Värmland. Kolsva feldspar mine, Västmanland. Routavaara quartz quarry, Jokkmokk.