Gemmological Characteristics And Color Mechanism Of Yanyuan Color Jade

Yanyuan color jade is a kind of new type of jade in the market in recent years,produced in yanyuan county,liangshan prefecture,sichuan province.Yanyuan color jade is colorful and rich in color,usually by yellow,green,purple,red purple,yellow green,white,pink and other colors gathered together,so it is also known as"colorful jade"or"yanyuan agate"by many locals.This article mainly by gem microscope,polarizing microscope,Fourier transform infrared spectrometer,micro Raman spectrometer,ultraviolet-visible spectrophotometer,X-ray powder diffraction,electronic probe and X-ray fluorescence spectrometer,testing technology such as differential thermal analysis study of YanYuan color jade stone mineralogical characteristics,and tries to probe into its color.The original stone of the salt source color jade is of egg type,with a layer of dark and thick oxide shell on the outside,and the overall lumpiness is smaller,more cracked,and the color is rich and diverse.The central part is mainly yellowish green,green and pinkish purple,while the outer part of the color ring is reddish purple and maroon.Under the polarized light microscope,the quartz particles were of very small isgranular structure with a particle size of about 20-200 meters.The infrared spectroscopy test shows that the main mineral composition of yanyuan color jade is a-quartz,and the crystallinity index of yanyuan color jade is about 6-7 by using the measurement and calculation method of the diffraction peak of the five fingers in XRD.Compared with the red agate in the warring states period,the crystallinity index of yanyuan color jade is higher and its density is better.Under the test of laser Raman spectrometer,it was found that the absorption peaks of goethite at242 cm-1 and hematite at 225 cm-1 and 608 cm-1 existed in the red,yellow-green and purple samples of yayuan caiyu,so it can be inferred that the main chromatism minerals of yayuan caiyu are related to hematite and goethite.According to the X-ray fluorescence spectrometer test,the main chemical composition of the salt-source color jade is SiO2,and the trace elements include Mn,Fe,Cu and so on.The main chromogenic element in red and purple salinized jade was Fe,and the chromogenic element was Cu in the yellow-green group.The structure water and crystal water were found in all the samples of yanyuan color jade,but the structure water and crystal water were the most in the yellow-green group.According to the analysis of uv-visible absorption spectra and uv-visible first-order derivative spectra,the characteristic peaks of the first-order derivative of hematite were found in red yanyuan caiyu at 555-595 nm,and the characteristic absorption peaks of goethite and Cu²⁺were found in yellow-green yanyuan caiyu.The characteristic peaks of the first derivative of hematite and Mn3+uv-visible characteristic absorption peaks with slight displacement were found in pink purple,reddish purple and deep purple salt-source color jade.It can be seen that red yanyuan colored jade is colored by hematite,yellow-green yanyuan colored jade is colored by goethite and Cu²⁺,and pink and purple yanyuan colored jade is colored by hematite and Mn³⁺.