Raman Spectroscopy of Nb,Ta-rich Cassiterite in Beauvoir and Montebras Granites,France

Cassiterites from both the Beauvoir and Montebras geanited of France are typically rich in trace elements such as Nb and Ta, and contain quite a number of inclusions of columbite (dominantly manganocolumbite).Two thin sections of cassiterite crystals have been prepared for Raman microprobe analysis).The spectra obtained from different parts of the cassiterites show that the vibra-tion frequency of the A1g peak decreases with increasing Nb ,Ta,Fe and Mn atomic contents.It is worthy to note that a new peak (named the “An peak”) has been reported for the first time in the part with oriented columbite inclusions.The vibration frequency varies from 827 to 830 cm^-1.The presence of th enew peak may be attributed to structural changes of cassiterite due to the excess of Nb and Ta in the lattice and the exsolution of columbite inclusions in cassiterite.

Raman spectroscopy of Nb,Ta-rich cassiterite in Beauvoir and Montebras Granites,France

Cassiterites from both the Beauvoir and Montebras granites of France are typically rich in trace elements such as Nb and Ta, and contain quite a number of inclusions of columbite (dominantly manganocolumbite). Two thin sections of cassiterite crystals have been prepared for Raman microprobe analysis. The spectra obtained from different parts of the cassiterites show that the vibration frequency of the A_ig peak decreases with increasing Nb. Ta, Fe and Mn atomic contents. It is worthy to note that a new peak (named the “An peak”) has been reported for the first time in the part with oriented columbite inclusions. The vibration frequency varies from 827 to 830 cm^-1. The presence of the new peak may be attributed to structural changes of cassiterite due to the excess of Nb and Ta in the lattice and the exsolution of columbite inclusions in cassiterite.