CassiteritesfromboththeBeauvoirandMontebrasgeanitedofFrancearetypicallyrichintraceelementssuchasNbandTa,andcontainquiteanumberofinclusionsofcolumbite(dominantlymanganocolumbite).TwothinsectionsofcassiteritecrystalshavebeenpreparedforRamanmicroprobeanalysis).Thespectraobtainedfromdifferentpartsofthecassiteritesshowthatthevibra-tionfrequencyoftheA1gpeakdecreaseswithincreasingNb,Ta,FeandMnatomiccontents.Itisworthytonotethatanewpeak(namedthe“Anpeak”)hasbeenreportedforthefirsttimeinthepartwithorientedcolumbiteinclusions.Thevibrationfrequencyvariesfrom827to830cm^-1.ThepresenceofthenewpeakmaybeattributedtostructuralchangesofcassiteriteduetotheexcessofNbandTainthelatticeandtheexsolutionofcolumbiteinclusionsincassiterite.
