Silicates: Brownite
Diagnostic card.
Mn Mn 6 O 8 SiO 4
Tsingonia tetragonal
Hardness 6-6,5
Specific weight 4,7-4,8
Cleavage is clear
Broken fracture
Black color
Glitter metal
This most common term denotes the Brownite-Longbinite group; It includes some very rare minerals that do not have a zero practical value. They are presented in the form of crystals of pseudo-octahedral bipyramidal habitus or in the form of dense granular aggregates. Color black or gray-brown, shine metallic.
Chemical composition. Manganese oxide (MnO) 44.8%, manganese oxide (MnO2) 55.2%; Often contains up to 8% silicon oxide and up to 10% iron. Fracture. Characteristic fracture has not. Form of crystalline precipitates. Pseudo octahedral crystals; Mostly found in dense grained masses. Class of symmetry. Tetragonal-skalenohedral - 42m. Cleavage. Notable for the octahedron (111).
Diagnostic signs.
Brownite does not melt in a candle flame and gives a gel-like residue when treated with hydrochloric acid. It is easily confused with magnetite, from which it is distinguished by the absence of ferromagnetism and association with manganese minerals. From Hausmanite (Mn3O4), with which it is almost identical in appearance, it can only be distinguished by X-ray diffraction and quantitative chemical analyzes. Hardly dissolves in HCl, in HNO3 decomposes into MnO and MnO2 (in the precipitate).
Origin.
Occurs in veins along with other minerals of manganese.
Place of Birth.
Brownite is found near Ilmenau in the land of Thuringia (Germany), in Jakobsberg (Sweden), Telemarken (Norway) and near Meson in Texas. Beautiful crystals are found in Langbana (Sweden) and Kacharwaki (India). In Italy, beautiful crystal formations are found in Val d'Aosta in Saint-Marcel.
Brownite. Longban, Sweden.
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Poisonous and radioactive dangerous stones and minerals
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Catalog of minerals and semi-precious stones of the world by groups
** - poisonous stones and minerals
** - radioactive stones and minerals
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