Mineral description : Uraninite

Uraninite (pitchblende) from Vall Fosca. Uraninite crystals from Varuträsk.

Mineral class Oxides : uraninite - ianthinite group

Chemical formula UO₂

Crystal system Cubic.

Habitus Cubical crystals in different modifications. As unregular grains or masses (pitchblende).

Cleavage Indistinct, fracture conchoidal to uneven.

Hardness 5-6

Density 7.5-9.7

Color Black

Streak Black to brownish black.

Luster Submetallic.

Description Uraninite is the main ore of uranium.

Occurance In pegmatites and hydrothermal veins. Also in sedimentary rocks.

Associates Gummite, uranophane.

Notes Strongly radioactive.
Insoluble in hydrocloric acid, but dissolves slowly in nitric acid.
If a drop of nitric acid is placed on top of uranite it becomes strongly flourescent.

Locations A very widespread mineral.

Billingen, Västergötland.
Västervik area.
Tåsjö, Västernorrland.
Varuträsk, Västerbotten. As cubes up to 5mm surrounded by yellow oxidation products.
Derome feldspar quarry, Varberg. As a rarity.
Digelskär, Gräsö, Roslagen. As pitchblende.
Håkanstorp iron mine, Åmmeberg. In veins and cracks.
Stripa and Blanka iron mines, Västmanland. In veins and cracks.

To oxides index.
Mineral group index.
Main index.

If you have some questions, suggestions or comments you are welcome to write me a line or two.

axelsson@acc.umu.se

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Last changed : 1998-03-07

Mineral class	Oxides : uraninite - ianthinite group
Chemical formula	UO₂
Crystal system	Cubic.
Habitus	Cubical crystals in different modifications. As unregular grains or masses (pitchblende).
Cleavage	Indistinct, fracture conchoidal to uneven.
Hardness	5-6
Density	7.5-9.7
Color	Black
Streak	Black to brownish black.
Luster	Submetallic.
Description	Uraninite is the main ore of uranium.
Occurance	In pegmatites and hydrothermal veins. Also in sedimentary rocks.
Associates	Gummite, uranophane.
Notes	Strongly radioactive. Insoluble in hydrocloric acid, but dissolves slowly in nitric acid. If a drop of nitric acid is placed on top of uranite it becomes strongly flourescent.
Locations	A very widespread mineral. Billingen, Västergötland. Västervik area. Tåsjö, Västernorrland. Varuträsk, Västerbotten. As cubes up to 5mm surrounded by yellow oxidation products. Derome feldspar quarry, Varberg. As a rarity. Digelskär, Gräsö, Roslagen. As pitchblende. Håkanstorp iron mine, Åmmeberg. In veins and cracks. Stripa and Blanka iron mines, Västmanland. In veins and cracks.