Mineral description : Pyrolusite

Pyrolusite from Harstigen.

Mineral class	Oxides : Pyrolusite - Manganite group
Chemical formula	MnO2
Crystal system	Tetragonal
Habitus	Dendritic or massive fibric aggregates. Crystals are prismatic but very rare.
Cleavage	Perfect, uneven fracture.
Hardness	2 (-6.5)
Density	5.2
Color	Matte black to dark gray.
Streak	Black to bluish black.
Luster	Metallic to earthy.
Description
Occurance	As dendritic forms in Dolomite cracks. As massive fibric aggregates. Pyrolusite is a secondary mineral in manganese occurances. Also forms asnodules in the oceans and as precipitate in lakes.
Associates
Notes	Soluble in hydrochloric acid.
Locations	Pyrolusite is a less common manganese ore in Sweden. Harstigen, Persberg. As dendrites in dolomite cracks. Bölet manganese mine, Undenäs, Västergötland. Spexaryd manganese mine, south Jönköping.

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