| 词条 | Braunite |
| 释义 |
| name = Braunite | image = Braunit - San Marcel, Piemont.jpg | imagesize = 260px | alt = | caption = Braunite, from San Marcel, Piemonte , Italy | category = Nesosilicates | formula = Mn2+Mn3+6[O8|SiO4] | molweight = | strunz = 9.AG.05 | dana = 7.5.1.3 | system = Tetragonal | class = Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) | symmetry = I41/acd | unit cell = | color = brownish black, steel-grey | colour = | habit = | twinning = | cleavage = {112} perfect | fracture = | tenacity = | mohs = 6-{{frac|6|1|2}} | luster = sub-metallic | streak = black | diaphaneity = opaque | gravity = 4.72 - 4.83 | density = | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = [1] | var1 = | var1text = }} Braunite is a silicate mineral containing both di- and tri-valent manganese with the chemical formula: Mn2+Mn3+6[O8|SiO4].[2] 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.[2] 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.[3][4] References1. ^[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Braunite Mineralienatlas] {{Refbegin}}2. ^1 Mindat 3. ^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 4. ^Mindat, Braunite-II
4 : Manganese minerals|Nesosilicates|Tetragonal minerals|Oxide minerals |
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