Methods for Identifying Polymer-filled Peristerite

Recently，National Gold & Diamond Testing Center（NGDTC）has encountered a string of feldspar beads with blue iridescence during a usual testing.Most of the beads display blue－white fluorescence of moderate intensity under the long－wave ultraviolet ray，and the fluorescence is linearly distributed in the beads.In order to name the feldspar sample accurately and find out the cause of the ultraviolet fluorescence，the beads have been investigated by conventional gemmological testing，electron microprobe and infrared spectrometer.The results show that the refractive index of the sample is about 1.53and that it has a layer structure and some needle inclusions under the microscope.With the results of electron microprobe，it can be decided that the sample is peristerite（albite with blue iridescence）.Moreover，based on the typical“earthworm movement”veins on the surface of the sample and the ultraviolet fluorescence from the fissures as well as the absorbed peaks at 3 053and 3 038 cm^－1 in the infrared spectrum，it can be concluded that the sample is polymer－filled peristerite.