Braunite is a silicate mineral containing both di- and tri-valent manganese with the chemical formula: Mn 2+ Mn 3+ 6 [O 8 |SiO 4]. [3] Common impurities include iron, calcium, boron, barium, titanium, aluminium, and magnesium.

After Wilhelm von Braun (* 1. October 1790 in Thal (Ruhla); † 6. February 1872 in Gotha), official and minister in Gotha, Germany, supporter of geology and mineralogy. He supplied the original material for the description of braunite. The Mn 2+ analogue of neltnerite. Compare also braunite-II.

Color: Dark, brownish black to steel-gray; in polished section, greyish white with a brownish tinge. Streak: Brownish black to steel-gray. Luster: Submetallic. Anisotropism: Weak in air to distinct in oil, dark to lighter slate gray.

Braunite occurs by metamorphism of manganese silicates and oxides; and also as a product of weathering. It is often associated with minerals such as pyrolusite, hausmannite, bixbyite, rhodonite, jacobsite, spessartine, and hematite.

Manganese oxide mineral deposits. Metamorphic and secondary weathering environments. Metamorphic, hydrothermal, and sedimentary rocks. Link to MinDat.org Location Data. Named after K. Braun (1790-1872) from Gotha, Germany. Comments: Crystals of braunite. Location: Black Rock Mine, Kalahari Manganese Field, Northern Cape Province, South Africa.

Has a doubled unit-cell parameter c by comparison to braunite. "The structure of braunite II, (...), is simply an intergrowth of slabs of bixbyite- and braunite-type structures, linked by the CaO 8 cubes of the latter." (Bevan and Martin, 2008).

The meaning of BRAUNITE is a brittle brownish black or steel-gray mineral that consists of manganese silicate and occurs massive and as tetragonal crystals (hardness 6—6.5, specific gravity 4.75—4.82).

Mar 1, 2018 · In this paper, we present the results of a detailed mineralogical and geochemical study performed on a braunite-rich deposit from southern Apennines (at Mormanno site, Italy), extensively exploited until the 70s and here described for the first time.

The structures of cubic and orthorhombic bixbyite (α–Мn 2 О 3), braunite, and probably braunite-II (Mn 2+ Mn 3+ 14 SiO 24), are related according to the space group Ibca. The regions in common include sheets of edge-and corner-linked octahedra (the A and A' sheets of bixbyite).

Jul 13, 2023 · This chapter describes the manganese ore Braunite (abbrv. bra), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks).