Gem mineralogy characteristics of Yunxiao garnet,Fujian,China
Yunxiao is a significant producing area of gem-quality garnet in China.However,the color origin of gar-net in this area remains ambiguous,which restricts the understanding of their formation mechanism and subsequent exploitation.In this paper,7 samples of orange-yellow-orange-red garnet from Yunxiao,Fujian were selected,and the spectral characteristics of the samples were analyzed by Fourier infrared spectrum,UV-visible spectrum and Ra-man spectrum,and the characteristics of main and trace elements were defined by electron probe(EPMA)and la-ser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)analysis.It is concluded that the color of the garnet is predominantly influenced by the absorption of visible light by Mn2+and Fe2+.Mn2+dictates the yellow tone of the garnet,while a minor amount of Fe2+governs the orange-red tone.Additionally,a trace amount of Ti4+imparts a brownish appearance to the garnet.The samples exhibited a relatively low manganese content and high iron and magnesium content in their core,a gradual increase in manganese content from the core to the rim.The samples also displayed a left-leaning partition pattern,with an enrichment of heavy rare earth elements and a deficit of light rare earth elements.Europium(Eu)showed a negative anomaly.These findings suggest that the garnets from Yunxiao,Fujian were formed during magmatic processes and are products of late-stage magmatic crystallization.
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