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Talc (Photo) [abbr. Tlc ]

Year of discovery: 1546 (World), 1889 (Japan)

Locality list: 444 localities of talc

• Mg₃Si₄O₁₀(OH)₂
• [Mg²⁺₃][(OH)₂|(Si₂O₅)₂]^6-

• Class: Talc-Pyrophyllite group
• Class: Phyllosilicate - Hydroxide
• Insoluble in: HCl
• Fluorescence: UV excitation (some examples, Yellow-Orange)
• Substitution pseudomorph: Replace Enstatite. (Agalite)
• Substitution pseudomorph: Replace Enstatite. (Bastite)
• Substitution pseudomorph: Replace Magnesite.

• Mg => Fe: Minnesotaite
• Mg => Ni: Willemseite

• Mg₃ => Fe₂: Ferripyrophyllite
• Mg₃ => Al₂: Pyrophyllite

• Color: Colorless, White, Pale green, Brown
• Streak: White
• Luster: Resinous
• Diaphaneity: Transparent-Translucent

• Habit: Platy

• Cleavage: Perfect on {001} (1 plane)
• Hardness: 1
• Density: 2.8

• System: Triclinic (1A), Monoclinic (2M, ?) (Layer-stacking polytype)
• Group: (-1), P(-1)
• Lattice: a=5.3, b=9.2, c=9.5, α=90.5, β=98.7, γ=90.1