Mineralogical Study Of Yellow Series Of Qingtian Stone From Zhejiang

Qingtian Stone is a famous seal stone in China,which is rich in color and fine in stone quality.On the basis of previous studies,this article uses polarizing microscope,X ray diffraction,infrared spectra,electron micro-probe,main,trace elements and rare earth elements analysis,hydrogen isotope analysis and other modern testing methods to analyze and study the Gemological,mineralogical and geochemical characteristics of Qingtian stone,in order to providing more data for the study of Qingtian stoneThis paper summarizes the gemological characteristics of Zhejiang yellow series Qingtian stone: the color is yellow to orange,with black,gray black,red,white and other miscellaneous colors;most of them are waxy luster,and some are oil luster when the structure is delicate;translucent to microtransparent,opaque in the black;the index of refraction is 1.54-1.59,the relative density is 2.79-2.86,and the hardness of Morse is 1.88-2.35;weak white fluorescence in the yellow,fluorescence inert in the orange,black or darker place.By means of polarizing microscope observation and back scattering image analysis,we can know the main structure of the yellow series Qingtian stone in Zhejiang is microscale structure,with residual porphyritic structure,granular structure,radial structure and so on.In addition,there are also dyed,veined,massive,spotted and other structural characteristics.By X-ray diffraction,infrared spectra and electron micro-probe analysis,the main minerals of the yellow series Qingtian stone in Zhejiang are pyrophyllite,sericite;the minor minerals are andalusite,Illite,quartz,apatite,pyrite,Barite,clinopyrite,zircon,hydroxytoparite,hematite,kaolinite,rutile,etc.Among them,pyrophyllite is mostly 2m type,which has higher order and can form high quality Qingtian stone.The content of mineral components in different colors was analyzed by electron micro-probe test.It can be seen that the origin of the yellow in Qingtian stone is related to the content of Fe,Ti,Cr in the crystal lattice of pyrophyllite as well as to the mechanical mixing of Fe elements between crystal particles.By means of X-ray diffraction and main elements analysis,the mineral composition ratio of the sample can be determined semi-quantitatively.Through the analysis of loss on ignition,it can be seen that there is also adsorbed water in Qingtian stone in addition to structural water.Based on the analysis of trace elements and rare earth elements,it is found that Qingtian stone is formed in the island arc volcanic rock of the tectonic environment of plate convergence boundary.It is characterized by the relative enrichment of light rare earth elements,the relative loss of heavy rare earth elements,and the characteristic of moderate Eu negative anomaly and ?Ce <1.Through the analysis of hydrogen isotopes,it can be concluded that the fluid source of Qingtian stone in the process of mineralization is atmospheric water.