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Coffinite

Year of discovery: 1956 (La Sal no.2 mine, USA), 1955 (Japan)

Locality list: 32 localities of coffinite

• U(SiO₄,OH)
• (U,Th)(SiO₄,OH)
• [U⁴⁺][(OH)_4x|(SiO₄)_1-x]^4-

• Class: Zircon group
• Class: Nesosilicate - Hydroxide
• Radioactive: Very strong

• U => Th: Thorogummite

• Color: Black, Dark brown
• Streak: Dark gray
• Luster: Metallic
• Diaphaneity: Opaque

• Cleavage: No
• Hardness: 5-6
• Density: 5.1

• System: Tetragonal
• Group: 4/mmm, I4₁/amd
• Lattice: a=7.0, c=6.3