四川石棉蛇纹石猫眼热相变的Raman光谱和XRD研究

Study on the Raman Spectra and XRD for Thermotransformation of Serpentine Cat’s Eye from Shimian, Sichuan Province, Southwest China

采用Raman光谱和X射线粉晶衍射(XRD)方法对四川蛇纹石猫眼的热相变过程和产物进行的研究表明,蛇纹石猫眼热相变的最终产物为镁橄榄石和顽火辉石。加热到500℃,蛇纹石猫眼的结构稳定;700℃,时,镁橄榄石的拉曼特征峰824cm-1和854cm-1出现,同时出现非晶质顽火辉石686cm-1和341cm-1附近的包络峰;800～900℃时,镁橄榄石的含量和结晶程度增强。晶质顽火辉石相出现,但强度较弱。1000℃时,镁橄榄石的含量明显降低。1100℃时,顽火辉石的含量和结晶程度显著增加。

Raman spectra and X-ray power diffraction (XRD) were used to study the process and products of thermotransformation of serpentine cat's eye, which was firstly discovered at the asbestos deposit of Shimian town, Sichuan Province, Southwest China and could display excellent cat's eye effect if polished properly. The results show that the final products of thermotransformation of the Sichuan serpentine cat's eye are crystalline forsterite and crystalline enstatite. Heated up to 500 ℃ for two hours, the Raman spectrum pattern of Sichuan serpentine cat's eye remains intact, indicating its stable internal structure and good resistance to relatively high heat; Up to 700 ℃, the characteristic Raman bands 824 and 854 cm -1 are clearly observed, indicating the appearance of forsterite, along with the appearance of the overlapped bands 686 and 340 cm -1 of noncrystalline enstatite; At 800~900 ℃, the crystallization of forsterite increases, meanwhile, crystalline enstatite begins to appear. When heated to 1 000 ℃, the amount of forsterite decreases apparently. Up to 1 100 ℃, the amount of enstatite increases rapidly.