Gemmological Characteristic of Peridot from Jiaohe,Jilin Province

Five peridot samples from Jiaohe，Jilin Province were tested in this paper.Conventional gemmological tests，USB4000，LA-ICP-MS，and Raman spectrometer were used for the research.Dominant wavelengths of peridot samples were measured in 550～590nm range according to USB4000，which show dominant hue is yellow colour and Fe is the colour-induced element.The results of LA-ICP-MS show that chemical formulas of two peridot samples are（Mg_1.780Fe_0.196Mn_0.003Ca_0.001）_1.980Si_1.008O₄and（Mg_1.790Fe_0.208Mn_0.003Ca_0.002）_2.111Si_0.997O₄ with their value of Fo approximately 90.It indicates that the origin mantle is transition-type.According to the content of CaO，it can be judged that the output of peridot is from the mantle xenolith.According to the content of Ni，the melting level of the basalts from the mantle is similar to that from Da Maping in Zhang Jiakou.Raman spectrometer was used to test samples in different directions.Difference in the vertical（001）is the largest，which is mainly due to the different direction of Si—O vibration while vertical（010）and vertical（100）are similar.We present a calibration for extracting olivine Fo contents（Fo＝Mg/（Mg＋ Fe）molar ratio；Fo₀-₁₀₀）from the peak positions of this doublet，permitting estimates of chemical composition from Raman spectra，and the value of Fo is 92and 88.