Braunite

Braunite is a <a href="/facts/Silicate/7NdthSRM">silicate</a> mineral containing both di- and tri-<a href="/facts/Valence_(chemistry)/ck7cHByj">valent</a> <a href="/facts/Manganese/j9ELd1TL">manganese</a> with the <a href="/facts/Chemical_formula/hghUtthl">chemical formula</a>:
Mn2+Mn3+6[O8|SiO4]. Common impurities include iron, calcium, boron, barium, titanium, aluminium, and magnesium.
Braunite forms grey/black <a href="/facts/Tetragonal/12Aop255">tetragonal</a> crystals and has a <a href="/facts/Mohs_hardness/wXBMcVIm">Mohs hardness</a> of 6 – 6.5.
It was named after the Wilhelm von Braun (1790–1872) of <a href="/facts/Gotha_(district)/kY7kLWdj">Gotha</a>, <a href="/facts/Thuringia/ozChAEWS">Thuringia</a>, <a href="/facts/Germany/paluuWBX">Germany</a>.
A calcium iron bearing variant, named braunite II (formula: Ca(Mn3+,Fe3+)14SiO24), was discovered and described in 1967 from Kalahari, Cape Province, <a href="/facts/South_Africa/vvXQpLgq">South Africa</a>.

Braunite open-in-new

Braunite