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Benjaminite

Year of discovery: 1924 (Silver Bear mine, Canada, Keeley-Frontier mine, Canada, and Outlaw mine, USA), 1997 (Japan)

Locality list: A locality of benjaminite

• Ag₃Bi₇S₁₂
• (Ag,Cu)₃(Bi,Pb)₇S₁₂
• [Ag⁺₃][Bi³⁺₇][S₁₂]^24-

• Class: Pavonite group < Large 2D fragment Pb sulfosalts < Sulfosalt class
• Class: Sulfosalt

• Color: Gray
• Tarnish: Dull gray, Yellow, Reddish brown
• Streak: Yellow-Pale brown
• Luster: Metallic
• Diaphaneity: Opaque

• Aggregate: Mixed with other similar mineral phases
• Twin: not rare

• Cleavage: Obvious, parallel to elongation
• Hardness: 3.5
• Density: 6.3

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=13.3, b=4.1, c=20.3, β=103.1

Etymology: Dr. Marcus Benjamin (1857-1932), curator of the National Museum of America, USA