Braunite Knowpia

Braunite
Braunite
	Braunite, from San Marcel, Piemonte , Italy
General
Category	Nesosilicates
Formula; (repeating unit)	Mn2+Mn3+6[O8\|SiO4]
IMA symbol	Bnt
Strunz classification	9.AG.05
Dana classification	7.5.1.3
Crystal system	Tetragonal
Crystal class	Ditetragonal dipyramidal (4/mmm) ; H-M symbol: (4/m 2/m 2/m)
Space group	I41/acd
Identification
Color	brownish black, steel-grey
Cleavage	{112} perfect
Mohs scale hardness	6–6+1⁄2
Luster	sub-metallic
Streak	black
Diaphaneity	opaque
Specific gravity	4.72 – 4.83
References

Braunite is a silicate mineral containing both di- and tri-valent manganese with the chemical formula: Mn²⁺Mn³⁺₆[O₈|SiO₄].^[3] Common impurities include iron, calcium, boron, barium, titanium, aluminium, and magnesium.

Braunite forms grey/black tetragonal crystals and has a Mohs hardness of 6 – 6.5.

It was named after the Wilhelm von Braun (1790–1872) of Gotha, Thuringia, Germany.^[3]

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.^[4]^[5]

References edit

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ Mineralienatlas
^ ^a ^b Mindat
^ JoHan P. R. De Viliers, The crystal structure of braunite II and its relation to bixbyite and braunite, American Mineralogist, Volume 65, pages 756–765, 1980
^ Mindat, Braunite-II

External links edit

Webmineral
Athena mineral

[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[2] Mineralienatlas

[Mindat-3] Mindat

[4] JoHan P. R. De Viliers, The crystal structure of braunite II and its relation to bixbyite and braunite, American Mineralogist, Volume 65, pages 756–765, 1980

[5] Mindat, Braunite-II

[3]

[1]

[2]

[4]

[5]

Summary

References edit

External links edit