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Simorre, Gers, Midi-Pyrénées, France
© J.Ralph
Much Occidental Turquoise is fossilized bone or teeth consisting of microcrystalline apatite. Originally thought to be coloured by vivianite, or perhaps by copper salts, recent research has suggested that the original material was fossilized mastodon ivory found in Miocene geological layers next to the Pyrrenean chain, France - which has been heated to induce the blue colour change. The material is almost entirely fluorapatite, with traces of Fe, Mn, Ba and U. Odontolite owes its turquoise-blue color to Mn5+ ions in a distorted tetrahedral environment of four O2– ions. Ref: American Mineralogist; November 2001; v. 86; no. 11-12; p. 1519-1524 |