The Collaborative International Dictionary
Braunite \Braun"ite\, n. (Min.) A native oxide of manganese, of dark brownish black color. It was named from a Mr. Braun of Gotha.
Wiktionary
n. (context mineral English) A silicate mineral containing divalent and trivalent manganese and forming grey-black tetragonal crystals.
Wikipedia
Braunite is a silicate mineral containing both di- and tri- valent manganese with the chemical formula: MnMn[O|SiO]. 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.
A calcium iron bearing variant, named braunite II (formula: Ca(Mn,Fe)SiO), was discovered and described in 1967 from Kalahari, Cape Province, South Africa.