Odontolite: Gemstone Information
Odontolite is not a distinct mineral species sensu stricto but a phosphate arising from fossil bones and teeth whose colour is provided by the iron phosphate vivianite (q.v.). It may resemble turquoise and has been called bone turquoise in the past. The hardness has been reported as near 5 and the SG near 3.00. The RI is 1.57–1.63; comparable figures for turquoise are close but the turquoise copper absorption spectrum is absent from odontolite. Included calcite may cause local effervescence with acids. Apatite may also be present.Odontolite has been found at Simmore, near Auch, Gers, France.Imitation odontolite has been made by calcining contemporary ivory and staining blue by soaking in a solution of copper sulphate.