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Topaz (Photo) [abbr. Tpz ]

Year of discovery: Prehistoric (World), 1877 (Japan)

Locality list: 144 localities of topaz

• Al₂SiO₄F₂
• Al₂SiO₄(F,OH)₂
• [Al³⁺₂][F₂|SiO₄]^6-

• Class: Topaz group
• Class: Nesosilicate - Fluoride
• Insoluble in: HCl
• Fluorescence: UV excitation (Some examples, Pale green-Yellow)
• Alter to Pyrophyllite.

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

• Habit: Prismatic
• Aggregate: Coating

• Cleavage: Perfect on {001} (1 plane)
• Hardness: 8
• Density: 3.6

• System: Orthorhombic
• Group: mmm, Pbnm
• Lattice: a=4.7, b=8.8, c=8.4

Etymology: Topazos (Searching) in Greek