Gemmological and Chemical Characteristics of Spessartine from Zambia

Abstract

The Lundazi region of Zambia is a relatively new source of spessartine. In this paper, a batch of orange-yellow garnet samples from this area were systematically studied in terms of chemical compositions and gemmological and spectral characteristics. Meaningful gemmological data were extracted, which enriched the information of origin tracing. Through conventional gemmological tests and chemical composition tests, it was determined that the orange-yellow garnet from Zambia is spessartine with a terminal component content of up to 92 mol.%. The test results of Raman spectroscopy and infrared spectroscopy showed that the three characteristic Raman peaks of spessartine are located near 907, 551 cm-1 and 349 cm-1. The characteristic infrared bands are near 976, 891, 865, 629, 571, 522 cm-1. By analyzing the attribution of UV-Vis absorption spectrum peaks of the spessartine samples from Zambia, the orange-yellow colour of the spessartine is caused by Mn2+ and Fe2+, and the corresponding absorption peaks are at 409, 421, 430, 460, 482 nm and 504, 525, 570 nm.