The Study On Gemological Mineralogy And Genesis Of Green Nephrite From Kutcho,Canada

Canadian green nephrite is favored by consumers because of its gorgeous color and high production.However,the research on Canadian Kutcho green nephrite is not thorough enough,this subject uses conventional gemological characteristics testing,observation under a polarizing microscope,infrared spectroscopy,and Raman spectroscopy,Electronic probe analysis and LA-ICP-MS and other test methods to conduct a statistical research and analysis of the mineral composition,chemical composition,and metallogenic characteristics of Canadian Kutcho green nephrite,combined with geological background,predecessor data,and compared with green nephrite around the world to discuss the genesis of green nephrite.Observation under microscope shows that Kutcho green nephrite has fewer color types,mainly green,bright green,and dark green.The color distribution is relatively even.Some samples have white bands,green spots,and black minerals on the green substrate.Among them,green spots and the black minerals are distributed like stars.Kutcho green nephrite have glass-grease luster,translucent-opaque,fine texture,refractive index 1.61-1.61,relative specific gravity 2.98-2.99.Observation results of microscope show that the main constituent minerals of Kutcho green nephrite are tremolite-actinolite homologous minerals.The structure of amphibole minerals can be divided into interlaced crystal structure,fibrous crystal structure and recrystallization structure,etc.Minor minerals include garnet and diopside.The formation stages of the minerals in the BSE image are:chromite,perovskite,tremolite-actinolite,and stress cracks can be seen in the garnet,which indicates the stress in the formation of green nephrite.Through infrared spectroscopy,Raman spectroscopy,electronicprobe,LA-ICP-MS test,it can be seen that the main component of Kutcho green nephrite is tremolite-acrite,the color of Kutcho green nephrite is mainly related to Fe and Cr,and the trace element Fe determines green nephrite appears green,and the trace element Cr determines the vividness of the green.However,the increase of Fe content will suppress the vividness of green nephrite and make the whole sample appear dark.TheFe/(Fe + Mg)ratio indicates that Kutcho green nephrite is a serpentine type green nephrite.The heavy rare earth elements in Kutcho green nephrite are slightly enriched,and the negative anomalies of Eu and Ce indicate that the Kutcho green nephrite mineralization is in a relatively reducing environment.The genesis of Kutcho green nephrite and ultramafic rocks eroded into serpentine in acidic reducing environment,and then eroded into green nephrite by multi-stage magma and hydrothermal action.The mineral composition comparison and principal component analysis models of green nephrite in various production areas show that the FeO content in Canadian Kutcho green nephrite,Canadian Arctic green nephrite,and Manas green nephrite is relatively high,and content is in the transition from tremolite to actinolite.