Tzankova N. 2008. Contemporary gemological alternatives of ivory. – Geology and mineral resources, 6, 29-33 (in Bulgarian with English abstract).
The ivory, composed by apatite Ca5(PO4)3(F, Cl, OH), is a traditional gemological raw material, suitable for carving or “scrimshaw” – an art of painting on ivory. In the few last years, high-quality ivory imitations are manufactured. They contain “filter” against yellowing. Several palm species are known to produce vegetable ivory (fruits and seeds), but the most important are Phytelephas aequatorialis and Metroxylon amicorum. Diagnostic features of the elephant ivory are its special microstructure, the smell in case of contact with a heated needle, investigation of the density, refractive index and other properties. The ivory jewels have to be protected from contact with detergents, sharp metal, and glass objects.
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