The Gemological Mineralogy And Spectroscopy Of Nephrite Cat's Eye And Serpentine Cat's Eye From Shimian, Sichuan Province, Southwest Of China

Nephrite cat's eye and serpentine cat's eye are very precious in jades and collection field.. Except for the Taiwan nephrite cat's eye and California serpentine cat's eye worldwide, the reports and studies about the two kinds of jades are very rare. This dissertation deals with the gemology and relative spectroscopy of these two cat's eyes, which were newly found in the serpentine asbestos deposit in Shimian town, Sichuan province, southwest of China. Also, the mechanisms of thermal-transformation of these two kinds of cat's eyes have been discussed. The study on the calculation of factor group of Raman spectrum in nephrite cat's eye, along with EMP and NMP of Sichuan serpentine cat's eye, is firstly reported.In this dissertation, polarized optical microscope,SEM,EPMA and XRD were adopted to determine the chemical and mineral composition of Sichuan serpentine cat's eye and nephrite cat's eye, as well as their internal structures. In addition, through tested FTIR,Raman spectra,EPR,NMP and UV-VIS, this dissertation studied these two cat's eyes [Si₄O₁₁] vibration modes and corresponding wave-number locations,the coloring elements and their position,the state of H₂O and its position,the mechanism of coloring in these two cat's eyes. Finally, the products and mechanism of the two cat's eye thermal-transformation have been discussed through the investigation of FTIR,Raman spectra and XRD at different temperatures. The results are as followings:The major chemical composition of Sichuan nephrite cat's is SiO2: 56.85-57.27 % ,MgO:21.61-22.99% and CaO:12.29-13.13%. It mainly consists of tremolites. Its lattice parameters calculated by XRD areα₀=0.984～0.985nm,ÑŒ₀=1.780～1.782nm,с₀=0.527～0.528nm andβ=106.13^O～106.35^O. Its general chemical molecule is (Ca_1.94Na_0.03)_1.97(Mg_4.63Fe_0.58Mn_0.02)_5.23[(Si_7.91Al_0.03)_7.94O₂₃].The mineral tremolite in Sichuan nephrite cat's eye is more like fiber than sheet and bunch. Fibroblastic texture is dominant texture, where Fiber-shaped tremolites are parallel to each other in the certain direction, that's why the nephrite can show the good effect of cat's eye, while the tremolites with relatively thicker fibers or bunchy and bundle fibers have the bad effect of cat's eye. The netted texture ,where tremolites arrange disorderly, has no effect of cat's eye. We firstly made the factor-group calculation of Sichuan nephrite cat's eye with group theory and obtained the general vibration modesΓ总=30Ag(R)+30Bg(R)+28Au(IR)+35Bu(IR),Γ内振动=20Ag(R)+19Bg(R)+19Au(IR)+20Bu(IR),which, theoretically, included 39 Raman vibrations and 39 IR vibrations.EPR was mainly caused by inclusion ions such as Fe and Mn. A Mn=83.2-90.2×10^-4T,g Mn =2.007-2.014; g Fe=4.126-4.167. Fe cation residing in M1 and M3 sites partly replaced Mg²⁺ in...