Gemmological and Mineralogical Characteristics of Dingqing Ivory-jade in Tibet

This deposit is located in Dingqing county, Tibet. Its texture is warm and delicate, and its color is like ivory, so it is named "Ivory jade". The ore is gravel-shaped, and some of it is round and oval. The gemmological and mineralogical characteristics of Dingqing Ivory-jade from Tibet are studied by means of UV-Vis Spectroscopy, X-ray Fluorescence Spectroscopy, Infrared Spectroscopy, XRD and SEM. The results show that: the Mohs hardness of Ivory-jade is 4~6, the relative density is 2.92~3.05, the refractive index is 1.62~1.70, no polychromism nor characteristic absorption band, the main mineral composition is magnesite (MgCO₃), with a small amount of quartz (SiO₂), trace calcite (CaCO₃). The gemmological and mineralogical characteristics of Dingqing Ivory-jade can be used as the basis of its origin identification.