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Hydroxylapatite (Photo)

Year of discovery: 1856 (World), 1893 (Japan)

Locality list: 37 localities of hydroxylapatite

• Ca₅(PO₄)₃(OH)
• Ca₅(PO₄,CO₃)₃(OH,F,Cl)
• Ca²⁺₅[OH|(PO₄)₃]^10-

• Class: Apatite group - Apatite supergroup
• Class: Phosphate - Hydroxide
• Variety: Carbonate-hydroxylapatite (+CO₃)
• Soluble in: HCl, HNO₃
• Substitution pseudomorph: Replaced by Turquoise.

• Polymorph: Hydroxylapatite-M

• Ca => Pb: Hydroxylpyromorphite

• PO₄ => AsO₄: Johnbaumite

• OH => F: Fluorapatite
• OH => Cl: Chlorapatite

• Color: White, Yellow, Green, Purple
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Opaque

• Habit: Hexagonal Prism, Tabular

• Cleavage: Poor on {0001} and {1010} (4 planes)
• Hardness: 5
• Density: 3.2

• System: Hexagonal
• Group: 6/m, P6₃/m
• Lattice: a=9.4, c=6.9

Synonym: Apatite-(CaOH) had been valid during 2008-2010.