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Gibbsite [abbr. Gbs ]

Year of discovery: 1822 (Richmond, USA), 1921 (Japan)

Locality list: 87 localities of gibbsite

• Al(OH)₃
• γ-[Al³⁺][(OH)₃]^3-

• Class: Hydroxide
• Soluble in: concentrated H₂SO₄
• Insoluble in: HCl
• Formed by alteration of Chalcoalumite.

• Polymorph: Bayerite (α, Monoclinic), Nordstrandite (β, Triclinic), Doyleite (δ, Triclinic)

• Color: White, Colorless
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Cleavage: Perfect on {001} (1 plane)
• Hardness: 2.5-3
• Density: 2.3

• System: Monoclinic
• Group: 2/m, P2₁/n
• Lattice: a=8.7, b=5.1, c=9.7, β=94.2