Gemmological Characteristic of Nanhong Agate from Liangshan in Sichuan Province, China and Africa

The nanhong agates from Liangshan in Sichuan Province, China and from Africa, were researched by using the conventional gemmological tests, electron microprobe (EPMA), X-ray fluorescence spectrometer (XRF), X-ray powder diffraction spectrometer (XRD), comprehensive thermal analysis (DSC/TG), and scanning electron microscope with energy spectrum analysis (SEM/EDS).The results indicated that the minerals of nahong agate samples are mainly α-SiO₂, including a few of elements Al, Mg, K, Na, Ca, S and Fe, Ni, Cu, Zn, etc..The content of Fe₂O₃ in the nanhong agates from Africa is higher than that of nanhong agates from Liangshan in Sichuan Province, which make the colour of nanhong agates from Arica deeper.The content of Al₂O₃ in the nanhong agates from Liangshan in Sichuan Province is higher than that of nanhong agates from Africa.Meanwhile, the crystallization of α-SiO₂ in nanhong agates from Liangshan in Sichuan Province is better than that of nanhong agates from Arica by DSC.