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Braunite (Photo)

Year of discovery: 1831 (Friedrichroda, Germany, Elgersburg, Germany, Öehrenstock, Germany, and Prabornaz mine, Italy), 1938 (Japan)

Locality list: 249 localities of braunite

• Mn₇SiO₁₂
• (Mn²⁺,Cu)Mn³⁺₆O₈(SiO₄)
• [Mn²⁺][Mn³⁺₆][O₈|SiO₄]^20-

• Class: Humite group
• Class: Nesosilicate - Oxide
• Soluble in: HCl
• Magnetism: Paramagnetic (Weak)

• Mn²⁺ => Cu: Abswurmbachite
• Mn²⁺ => Ca: Neltnerite

• Color: Dark brown, Black
• Streak: Dark grayish brown
• Luster: Sub-Metallic
• Diaphaneity: Opaque

• Habit: Bipyramidal
• Aggregate: Earthy

• Cleavage: Perfect on {112} (2 planes)
• Hardness: 6-6.5
• Density: 4.8

• System: Tetragonal
• Group: 4/mmm, I4₁/acd
• Lattice: a=9.4, c=18.8

• Coexist: Quartz

Etymology: Dr. Kammerath Braun (1790-1872), German mineralogist