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Alloclasite

Year of discovery: 1866 (Elizabeth mine, Romania), 1971 (Japan)

Locality list: 4 localities of alloclasite

• Co₃Fe²⁺As₄S₄
• (Co,Fe²⁺)AsS
• [Co₃][Fe²⁺][As₄S₄]

• Class: Sulfide

• Co => Fe: Arsenopyrite

• Co₃Fe => Co₂Fe₂: Glaucodot (Polymorph?)
• Co₃Fe => Co₄: Cobaltite

• Color: Dark gray-Silver
• Streak: Black
• Luster: Metallic
• Diaphaneity: Opaque

• Habit: Prismatic, Acicular elongated to [010]
• Aggregate: Radial, Bunched

• Cleavage: Perfect on {101} (1 plane), Distinct on {010} (1 plane)
• Hardness: 5
• Density: 6.0

• System: Monoclinic
• Group: 2, P2₁
• Lattice: a=4.7, b=5.6, c=3.4, β=90.2

Etymology: Destruction in Greek