The Gemological Characteristics Research And Quality Evaluation Of Chengde Jade

This paper conducts a preliminary investigation on the geological conditions of Chengde jade mining area,using Fourier transform infrared spectrometer,X-ray diffractometer,X fluorescence spectrum analyzer,polarizing microscope and other testing techniques to systematically study Chengde jade and evaluate its quality.The mineral composition and composition research results show that the main mineral composition of"Chengde Jade"is serpentine,calcite and brucite,the main chemical components are Mg O,Si O₂and Ca O,and the minor components are Al₂O₃,Fe₂O₃,Mn O,Ti O₂,Zn O and so on."Chengde Jade"is divided into two categories:calcite jade and serpentine jade.Calcite jade is divided into calcite jade,serpentine calcite jade and brucite calcite jade,mainly in black,white,gray,pink white and other colors.Structural characteristics studies have shown that serpentine calcite jade has a common granular micromorphic structure and fine-grained metamorphic structure;brucite calcite jade is dominated by a granular micromorphic structure and a leaf-like granular micromorphic structure.Hardness and density tests show that the hardness of calcite jade is between 3-6 and the density is between 2.483-2.636g/cm³.Serpentine jade is divided into serpentine jade and calcite serpentine jade,common colors such as green,yellow-green,dark green,and brown,and a few colors such as white and pink.Serpentine jade has a microscopic metamorphic structure,and the common forms are scale,leaf and fibrous;calcite serpentine jade has a microscopic metamorphic structure and a fine-grained metamorphic structure.Serpentine jade has a hardness of 3-5and a density of 2.510-2.682g/cm³.Most of the samples of"Chengde Jade"present a waxy luster,slightly transparent or opaque,and a small part are translucent.The refractive index of"Chengde Jade"is between 1.53-1.58,has no characteristic absorption spectrum,and the whole is luminous and inert.In"Chengde Jade",the quality of serpentine jade is better than that of calcite jade.Serpentine jade is compared with Xiuyan jade,Taishan jade,Qilian jade and Anlv jade.The color is richer,the transparency is slightly worse,the gloss and hardness are average,and some of them have fine texture,which are better than Taishan jade,Qilian jade and Anlv jade.Among the calcite jade,the serpentine calcite jade is compared with the Lantian jade.The composition,structure,color,hardness and fineness of the texture are similar,and the transparency and gloss are slightly worse.Some have a microscopic metamorphic structure,and the texture is better than that of the Lantian jade.Brucite calcite jade is a new type of jade,and no relevant public reports have been seen in China.