Odontolite

Odontolite, also called bone turquoise or fossil turquoise or occidental turquoise, is fossil bone or ivory that has been traditionally thought to have been altered by turquoise or similar phosphate minerals such as vivianite.

Odontolite
General
Category	Phosphate minerals
Formula	Ca5(PO4)3[F, OH, Cl] Fe2+ 3(PO 4) 2·8H 2O
Strunz classification	8.DD.15
Crystal system	Triclinic
Crystal class	Pinacoidal (1) (same H–M symbol)
Identification
Colour	Turquoise, blue, blue-green, green
Crystal habit	Massive, nodular
Cleavage	Perfect on {001}, good on {010}, but cleavage rarely seen
Fracture	Conchoidal
Mohs scale hardness	5
Luster	Waxy to subvitreous
Streak	Bluish white
Diaphaneity	Opaque
Specific gravity	3–3,2
Optical properties	Biaxial (+)
Refractive index	nα = 1.610 nβ = 1.615 nγ = 1.650
Birefringence	+0.040
Pleochroism	Weak
Fusibility	Fusible in heated HCl
Solubility	Soluble in HCl
References	[1][2][3]