Braunite

noun

1. A native oxid of manganese, containing also 20 per cent. of manganese silicate.
2. It occurs in tetragonal crystals of a brownish-black color in Thuringia, the Harz, Piedmont, and elsewhere.
3. A native oxide of manganese, of dark brownish black color. It was named from a Mr. Braun of Gotha.
4. A silicate mineral containing divalent and trivalent manganese and forming grey-black tetragonal crystals.