Study on Gemmological Characteristics of Red Feldspar

A type of red and transparent feldspar has recently appeared on domestic and overseas gem markets, whose natural characteristic is much controversial.For studying the origin of the red colour, the gemmological characteristics, chemical compositions and UV-VIS absorption spectra are tested by using the conventional methods, LA-ICP-MS and UV-VIS spectrophotometer.The results show that the red feldspar samples belong to andesine.Compared with the yellow feldspar samples, the content of Cu is 739×10^-6~801×10^-6 in the red feldspar samples, which is more higher than that in the yellow feldspar samples (1.07×10^-6), and the contents of the other elements have no significant differences.Therefore, the colour of the red feldspar samples may be related to the Cu.The results of the UV-VIS absorption spectra indicate that the red feldspar samples have the absorption band at 566 nm, which is due to intrinsic absorption of light caused by Cu.