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Bournonite

Year of discovery: 1805 (Wheal Boys (Trewetha mine), UK), 1910 (Japan)

Locality list: 27 localities of boulangerite

• PbCuSbS₃
• [Pb²⁺][Cu²⁺][Sb³⁺][S₃]

• Class: Bournonite group < Ternary sulfosalts < Sulfosalt class
• Class: Sulfosalt
• Insoluble in: HCl
• Substitution pseudomorph: Replaced by Cerussite or Oxyplumboroméite (Oxyplumboromeite).

• Sb => Bi: Aikinite
• Sb => As: Seligmannite (Series)

• Color: Steel gray-Black
• Streak: Steel gray-Black
• Luster: Metallic
• Diaphaneity: Opaque

• Habit: Short Prismatic, Long Tabular
• Aggregate: Columnar
• Twin: {110} repeated to form cross or gear like appearance

• Cleavage: Perfect on {100} and {001} (2 planes), Imperfect on {010} (1 plane)
• Hardness: 2.5-3
• Density: 5.8

• System: Orthorhombic
• Group: mm2, Pmn2₁
• Lattice: a=8.2, b=8.7, c=7.8

Etymology: Count Jacques Louis de Bournon (1751-1825), French crystalographist and mineralogist