Analysis Of The Color And Structure Of Qin Ziyu

This article takes Qin Ziyu from Luonan County,Shaanxi Province as the research object,through the use of conventional gemological instruments,polarizing microscope,X-ray diffractometer,X-ray fluorescence spectroscopy,electron probe,infrared spectroscopy,laser Raman,ultraviolet-visible spectrophotometer The gemological characteristics,microstructure,mineral composition,chemical composition and spectral characteristics of Luonan Qin Ziyu were studied in detail with other instruments and equipment,and the color origin and structure analysis were discussed.Qin Ziyu is dominated by maroon-red-purple,blue-green-gray-green,white,occasionally yellow,part of it contains black impurities,and has the characteristics of red hearts with green edges and purple hearts with white edges.Under the gemological microscope,the red and green areas can be seen to have distinct color clusters.The red is disseminated and the green is distributed in clumps;and under the polarized light microscope,red granular aggregates and green scaly aggregates can be seen;According to the measurement,Qin Ziyu's quartz grains are mainly 5-20?m in size,some up to 200?m,and more than 90%are granular structures,including three types ranging from coarse to fine:apparent crystalline,microcrystalline-cryptocrystalline,and cryptocrystalline.The structural characteristics are mainly cryptocrystalline,and the degree of cryptocrystalline is positively related to the transparency and texture of the appearance of Qin Ziyu jade.Through X-ray powder crystal diffraction analysis,it is concluded that the sample of Qin Ziyu contains?-quartz,hematite,chlorite,and mica,and the crystallinity range of 8.83?9.55 is calculated by the"five-finger peak",which shows that the quartz in the sample is in the range of8.83?9.55.The degree of crystallinity is relatively high.The electronic probe test results show that the main component of the different color parts of the quartz in Qin Ziyu is SiO₂,the mass fraction is between 94.68%and 99.92%,and contains some trace elements and a small amount of impurity minerals,including K,Ca,Na,Mg,Al,Fe,Ti,Mn,Cr,etc.,there are iron minerals and calcite in the red area,and sericite in the green area.The chemical formula is calculated as K0.77(Al1.90,Fe0.05,Mg0.05)?=2.00(Si3.22Al0.78)?=4O10(OH)2.X-ray fluorescence spectroscopy shows that the content of Fe,Al,Ti,and K in the brown-red sample is higher,and the content of Fe,Ca,Mn,and Cu in the purple-red sample is higher.Corresponding band-like distribution occurs along with the color change.The belt gradually enriched.The infrared spectrum test results show that the main absorption peaks of Qin Ziyu are 480cm^-1,536 cm^-1,779 cm^-1,798 cm^-1,1107 cm^-1,1215 cm^-1,which are the characteristic infrared absorption spectra of?-quartz.Raman spectroscopy test results show that the iron minerals in the red area of Qin Ziyu are hematite,the green areas are sericite and chlorite,the black impurities are carbonaceous,the yellow areas are dolomite,and the colorless minerals in the surrounding rock are calcite.Through the ultraviolet-visible light spectrum test and the first-order guided spectrum,it can be seen that the absorption peak of 567?584nm in the red region is mainly caused by hematite,and the sample with a purple tone has an absorption band of 542nm.Through the comprehensive analysis of the above tests,it can be seen that the main component of Qin Ziyu is?-quartz(excluding clinosil),with a granular cryptocrystalline structure as the main component,with high crystallinity.The red area is colored by hematite,the green area is colored by sericite and chlorite,and the purple hue is related to the replacement of Si by Fe ions.