The Gemological And Origin Of Color Datong Ziyu

In this thesis,in order to get a comprehensive understanding of its gemological characters and discuss the origin of its purple coloring,by using a series of experimentssuchasMetallurgicalMicroscopy,polarizing microscopy,SEM(Scanning Electron Microscopy),Cathode Luminescence,EPMA(Electron Probe micro-analyzer),infrared spectroscopy,UV-Vis-NIR Spectrophotometer,Laser Raman spectroscopy,Fiber Optic Spectrometer,Differential Thermal Analysis,LA-ICP-MS(Laser Ablation-Inductively Coupled Plasma-Mass Spectrum).Datong jade is a kind of saphenous quartz jade,with different deep and shallow purple,yellow brown or gray and white color,glass luster,transparent to translucent,some dehydrated material is weak glass luster,with a sense of glial.Datong purple jade is mainly massive and globular in the cavities or cracks of basalt formed after volcanic eruption.Located about 1 m from the basalt wall,Datong purple jade is mostly massive,with high grinding roundness and small block.The refractive index of Datong purple jade is similar to that of general quartz jade,the refractive index is 1.54?1.55,the relative density is 2.65,and the Morse hardness is 6.88?6.93.No characteristic absorption spectrum,all bright in polarizer and inertness under short and short wave of UV fluorescent lamp.The color of Datong purple jade was uniform,and quartz particles were found in some samples.The particle size was about 5?7 mm.There were many erosion pits of different sizes on the surface of the samples,and white material was filled in the pits.Under gemstone microscope,silica appears fine granular,short fibrous,long fibrous and crystalline quartz in orthogonal polarized light.The short fiber and long fiber structure can be arranged in parallel or concentric circle.Under SEM,it was found that two samples of Datong purple jade with different color depth were unordered stacking of small globules of less than 1?m,and there was no obvious difference in the arrangement of small spheres.The cathodic luminescence of Datong purple jade is weak,most of the areas are not luminous,the area of iron infection is weak blue purple fluorescence,and the black vein appears bright and strong orange yellow fluorescence,which is the characteristic luminescence phenomenon of carbonate.The mineral composition of Datong purple jade is?-quartz,which is consistent with the infrared absorption spectrum and Raman absorption spectrum of standard quartz.In addition,there is a small amount of orthosilicate,characterized by 502cm^-1in Raman spectra.The Lorentz peak area fitted by Origin Lab is used directly and the content of A₅₀₁/A₄₆₄orthosilicate is approximately 30%-50%.By comparing and analyzing the data of UV-Vis spectrophotometer and optical fiber spectrometer with the electron probe LA-ICP-MS,the main wavelength of the sample is from 440 to 475nm,and the calculated hue angle is in the range of 280°-290°.The color of Datong purple jade is caused by the hole color center of Fe?Mn.The results show that the main wavelength of the sample is significantly correlated with the color of most of the samples.The Pearson coefficients are-0.81775?0.98859,respectively,and the content of Fe?Mn in the sample increases with the darker purple tone.