1) Phosphate mineral 
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. ...
• (n.) A fossil tooth colored a bright blue by phosphate of iron. It is used as an imitation of turquoise, and hence called bone turquoise.
fossil bone or tooth that consists of the phosphate mineral apatite (q.v.) coloured blue by vivianite. It resembles turquoise but may be ... [1 related articles]
O·don'to·lite noun [ Odonto- + -lite .] (Min.) A fossil tooth colored a bright blue by phosphate of iron. It is used as an imitation of turquoise, and hence called bone turquoise .