Gemological characteristies and color genesis of green Miyu jade from Henan,China
Henan Miyu jade is an important variety of jade in China,which belongs to the phanerocrystalline quar-tzite.A systematic geological study of the Miyu jade deposit in Xinmi City,Henan Province,has been carried out,but its gemmological characteristics and color genesis remain controversial.This paper synthesizes the research re-sults of the previous researchers,and obtains the gemological characteristics,spectroscopic research characteristics and chemical composition characteristics of the green series of Henan Miyu jade samples by routine gemological tes-ting,FTIR spectroscopy,UV-Ⅵs spectroscopy,Raman testing and electron microprobe testing.The results show that Miyu jade is a quartzite with good crystallinity.The main mineral component is α-quartz,and minor minerals include muscovite,hematite,carbonaceous minerals,rutile,tourmaline,etc.It has a granular metamorphic struc-ture and a microscopic fine-grained metamorphic structure.Significant characteristic absorption peaks of Cr3+were seen in the UV-visible spectrum.The green color of Miyu jade is related to chromium-containing white mica,and the green color of chromium-containing white mica is caused by the trace elements it contains,such as Cr,V,Ni and other color-causing elements.The darker the green color,the higher the content of Cr,Ni and V.With the increase of Fe3+content,the yellow tone of the sample is more obvious.
green Miyu jadequartzartzite jadegemological characteristicscolor genesisHenan
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