Odontolite

Chemistry: Fossilized bones and teeth of pre-historic vertebrates; stained blue by vivianite.
Crystal system: Amorphous; may show features of tooth and bone structure.
Color: Opaque; blue, greenish blue.
Hardness: 5
Cleavage: -
Specific gravity: 3 – 3.15
Refractive index: 1.57 – 1.63 variable
Luster: -
Dispersion: -
Dichroism: -
Occurrence: Miocene sediments of Simorre near Auch, France; also associated with fossilized remains of Siberian mammoths.

Notes
Also known as ‘bone turquoise’; imitated by staining calcined teeth with copper sulphate solution (SG: 1.8; RI:1.54; similar to bone or ivory).