Mineral Components and Identification Characteristics of Sugilite Jade

Nowadays, sugilite jade is an emerging gemstone in jewelry market, which is just identified by its colour with experiences.The gemmological and mineralogical researches of the sugilite jade are few.In this paper, the mineral components, chemical compositions, IR and XRD spectra of the sugilite jade samples are tested by using the polarizing microscope, Fourier transform infrared spectrometer (FTIR), Electron microprobe (EMP) and X-ray powder differaction (XRD) .The results show that the sugilite jade samples mainly consist of sugilite and quartz, with a small number of feldspar, chlorite and limonite.The sugilite is of lath-like or cryptocrystalline aggregates and the quartz is equiaxed particulate or irregular-shaped mass and band.The chemical formulation of the sugilite is K_0.94Na_2.86Li_2.49 (Fe³⁺_1.59Mg_1.82)_3.41Al_0.22Ca_0.26Si_11.02O_30.00H₂O, whose IR characteristic peaks are at 455, 507, 588, 653, 694, 777, 797, 1 042, 1 123 cm^-1, and XRD diagnostic peaks are at 4.323 (100), 4.063 (57), 3.197 (81), 2.863 (51) .The content of MnO in sugilite could directly influence the colour of the sugilite jade, and the IR, XRD of the sugilite are one of the identification characteristics for the sugilite jade.