[Vibration spectra and genetic type of cassiterites].

Trace elements determination of cassiterites from Furong ore field indicates that there is a certain amount of Fe, Mn and Ti elements in cassiterite. The mean of unit-cell parameters for cassiterite is 7.165 (nm3) by the method of XRD analysis and the unit-cell parameter which also indicates that the genetic type of the ore field belongs to cassiterite-sulfide type, is bigger than that of other genetic type. Four IR active vibration frequencies in cassiterite samples also suggest that the IR spectra of cassiterites from Furong ore field belongs to deformed spectra suggesting that the genetic type of cassiterite from Furong ore field is mainly of cassiteriate-sulfur type. The Raman frequency of A1g peak has typomorphic significance to study its genetic type. A1g is a characteristic peak of cassiterite and AO2 oxide of the same structure style. Impure elements of cassiterite remarkably affect its Raman frequency which will move to low frequency if the contents of Nb and Ta reach a certain amount. In Furong ore field, A1g frequency of casstiterite is about 632 cm(-1) which is bigger than other cassiterites of various genetic types and the implication and character of Raman spectra are consistent with the cell parameters and IR analysis of these samples. Combined with the study of chemical composition and crystal structure, the IR spectra and Raman spectra can mean a lot for the analysis of genetic type of the cassiterite.