A Preliminary Study On The Types And Causes Of Jadeite "Cotton Wadding" In Myanmar

Jadeite is a polycrystalline mineral aggregate composed of pyroxene minerals mainly composed of jadeite minerals.Myanmar is the main producing area of jadeite.However,in recent years,the resources are continuously exhausted,and the high-quality jadeite is gradually decreasing.Many Jadeites with defects in the market have become new favorites,and jadeite with "cotton wadding" is one of them.The output of "cotton wadding" of jadeite has different ways of expression,which also has different effects on the quality evaluation of jadeite.Through the systematic analysis of the output characteristics of different types of "cotton wadding",this paper makes a new classification and Research on the "cotton wadding" of jadeite according to the causes and output characteristics,and probes into the causes of different types of "cotton wadding" and their relationship with jadeite,so as to provide corresponding scientific basis for the quality evaluation of jadeite.According to the different types of cotton wadding,it can be divided into "structural cotton" and "mineral cotton" “ The "structural cotton" is mainly caused by the different size and combination of jadeite,the main mineral of jadeite“ "Mineral cotton" is mainly the "cotton wadding" produced by the difference of refractive index and mineral fabric due to the existence of other minerals in Jadeite mineral assemblage.Based on the test and analysis of two kinds of different "cotton wadding" characteristic jadeite samples containing "structural cotton" and "mineral cotton",the following research results are obtained:1.The luster of the "cotton wadding" part of jadeite containing "structural cotton" is consistent with that of the main part,and the refractive index and relative density are within the normal range of jadeite;The luster of "cotton wadding" part of jadeite containing "mineral cotton" is weaker than that of the main part of jadeite,and the relative density and refractive index are lower than the standard value of jadeite..2.Through the observation of microstructure,the "cotton wadding" part of jadeite containing "structural cotton" and the main part of jadeite are mainly composed of jadeite minerals,mainly with residual crystalloblastic structure of large particles and fine-grained intertwined crystalloblastic structure of fine particles;the "cotton wadding" part of jadeite containing "mineral cotton" is similar to nepheline in optical characteristics,while the main part of jadeite is still mainly composed of jadeite minerals,it is mainly composed of fine-grained meta crystalline structure.3.The results were analyzed by infrared spectroscopy,laser Raman spectroscopy,X-ray diffraction,electron probe and laser ablation plasma mass spectrometry,it can be concluded that the "cotton wadding" part of jadeite containing "structural cotton" and the main part of jadeite are the same phase composition,mainly jadeite minerals;The "cotton wadding" part of jadeite containing "mineral cotton" is mainly composed of nepheline mineral,and the main part of jadeite is mainly composed of jadeite mineral.At the same time,the contents of Mg,Cr,Fe and Sr in the white "cotton wadding" part of jadeite containing "structural cotton" are lower than those in the main part of jadeite.4.Through the genetic analysis of "structural cotton" and "mineral cotton",it is found that "structural cotton" is mainly due to the "cotton wadding" of jadeite minerals in different stages,which is the residual form of early jadeite,including micro fracture cotton,mineral interstitial cotton and mineral inclusion cotton,Because the jadeite of early diagenetic stage is recrystallized and refined by later diagenetic stage,the residual of diagenetic stage forms "cotton wadding".The more the residual,the more the "cotton wadding",and vice versa“ "Mineral cotton" is mainly associated minerals different from jadeite due to crystallization differentiation in the later stage of jadeite formation.The difference of refractive index between jadeite and jadeite results in "cotton wool" with different light and shade in vision;It is found that there are nepheline and other feldspar minerals in the mineral wool,which are potassium rich nepheline by EPMA analysis.It is speculated that the "cotton wadding" formed by the crystallization of nepheline minerals in the environment of low silicon and high potassium.5."Cotton wadding" has a certain impact on the quality evaluation of jadeite,but if the "cotton wadding" is skillfully designed and carved,and fully utilized,it can present a different aesthetic feeling and improve the quality of jadeite.