Braunite is a

silicate In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is a ...

mineral containing both di- and tri- valent

manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

: Mn²⁺Mn³⁺₆ SiO₄Mindat
/ref> Common impurities include iron, calcium, boron, barium, titanium, aluminium, and magnesium. Braunite forms grey/black

tetragonal In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a squar ...

crystals and has a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by ...

of 6 - 6.5. It was named after the Wilhelm von Braun (1790–1872) of

Gotha Gotha () is the fifth-largest city in Thuringia, Germany, west of Erfurt and east of Eisenach with a population of 44,000. The city is the capital of the Gotha (district), district of Gotha and was also a residence of the Ernestine House of Wet ...

Thuringia Thuringia (; german: Thüringen ), officially the Free State of Thuringia ( ), is a state of central Germany, covering , the sixth smallest of the sixteen German states. It has a population of about 2.1 million. Erfurt is the capital and lar ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

. A calcium iron bearing variant, named braunite II (formula: Ca(Mn³⁺,Fe³⁺)₁₄SiO₂₄), was discovered and described in 1967 from Kalahari, Cape Province,

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

.Mindat, Braunite-II
/ref>

References

External links

WebmineralAthena mineral
Manganese(II,III) minerals Nesosilicates Tetragonal minerals Minerals in space group 142 Oxide minerals {{silicate-mineral-stub