Abstract:
BACKGROUNDThe Xichuan turquoise mining area in Henan Province belongs to the east extension of the turquoise metallogenic belt in the junction of Hubei and Shaanxi Provinces. A lot of turquoise artifacts have been excavated in many early archaeological sites near Xichuan. Therefore, the distribution of the Xichuan turquoises has attracted wide attention of many archaeologists.
OBJECTIVESTo study mineralogical characteristics of Xichuan turquoise in order to improve the mineralogical study of turquoise in different mining areas in China and provide important data support for tracing the mineral resources of early turquoise artifacts in China.
METHODSTechnologies including polarizing micro-scope, scanning electron microscope, X-ray diffraction were applied to study the texture and structure of turquoise. Electron probe microanalysis and back scattered electron imaging were applied to study the mineral assemblage of Xichuan turquoise.
RESULTSXichuan turquoise, ring-like, nodular and patchy granular was primarily composed of fine scaly, short columnar and lamellar microcrystalline aggregates. By comparing the microcrystalline structures of different samples, it was noted that the sizes, shapes and distributions could affect the densification and color of Xichuan turquoise. Quartz, chalcedony and iron oxide were common in the Xichuan turquoise aggregate. Svanbergite could also be observed in some samples.
CONCLUSIONSBy comparing the mineral assemblages of turquoise in other mining areas, it was found that Xichuan turquoise was similar to the turquoise in Hubei Province with quartz and limonite as main mineral impurities, different from the turquoise in Anhui Province with kaolinite as main mineral impurities.