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Beidellite [abbr. Bei ]

Year of discovery: 1925 (Beidell, USA), 1937 (Japan)

Locality list: 10 localities of beidellite

• Na_0.3Al_2.3Si_3.7O₁₀(OH)₂,nH₂O
• (Na,Ca_0.5)_0.3Al₂(Si,Al)₄O₁₀(OH)₂,nH₂O
• [Na⁺_0.3][Al³⁺₂][(OH)₂|Al_0.3Si_3.7O₁₀]^6.3-,nH₂O

• Class: Dioctahedral < Smectite group < Mica supergroup
• Class: Phyllo-aluminosilicate - Hydroxide

• Al₂ => Zn₃: Sauconite
• Al₂ => Na_0.03(Al,Mg)₂: Montmorillonite (Series)

• Na_0.3Al₂ => Ca_0.25Mg₃: Saponite (Series)

• Color: White, Pale brown, Dark brown
• Streak: White
• Luster: Earthy
• Diaphaneity: Translucent

• Cleavage: Perfect on {001} (1 planes)
• Hardness: 1-2
• Density: 2.1

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=5.2, b=9.0, c=17.6, β=90.0