Raman Spectral Analysis on a Special Band of Nanhong Agate
GUO Mei1, WANG Wen-wei2, LIU Hao1, LU Zhuo2, YIN Zuo-wei1*
1. Gemmological Institute, China University of Geosciences (Wuhan), Wuhan 430074, China
2. Jewelry School, West Yunnan University of Applied Sciences, Tengchong 679100, China
Abstract：Nanhong agate is a special kind of agate, because of its moist texture and bright color, it is accepted by most consumers. Special band with transparent edges and the obvious inner boundary is often found in Nanhong agate, which is rarely mentioned in the study of Nanhong agate. This article uses micro-laser Raman spectroscopy and scanning electron microscopy to analyze this band. The test results show that the difference between the outer side (sectionⅠ) and the inner side (sectionⅡ) of the Raman spectrum is the change in the strength of the 503 cm-1 peak and the degree of the splitting of the 400 cm-1 peak. The results of the two samples showed that the strength of the 503 cm-1 peak gradually decreased from the outside to the inside and disappeared, and the regular change of the 400 cm-1 peak in the section Ⅰ and Ⅱ. The characteristic peak of 503 cm-1 represents a kind of silica mesophase mineral-moganite, and it also shows that the content of moganite gradually decreases from the outside to the inside until it disappears. The splitting degree of 396 and 402 cm-1 in 400 cm-1 increases with the decrease of the peak strength of 503 cm-1, and the difference in the splitting degree of 400 cm-1 reflects the crystallinity of agate, so it is inferred that there is a certain correlation between its crystallinity and the content of moganite. WeSelect YND-6 # 2 to calculate the content of moganite, by simulating the relationship function between the peak intensity ratio of I(503 cm-1)/I(465 cm-1) and the content of moganite, the maximum of moganite content is calculated as 11.67%, indicating that it forms a non-evaporating environment. Scanning electron microscopy results showed that the size, order of arrangement, and self-profiling of the particles increased from section Ⅰ to sectionⅡ, indicating that the crystallinity increased from section Ⅰ to section Ⅱ. In summary, the regular changes in the content of moganite and the degree of crystallinity in the band of Nanhong agate, as well as the difference in micro-morphological and appearance between the band and the inner side, indicate that it is in different growth stages.
Key words：Nanhong agate; Band; Moganite; The degree of crystallinity
郭 梅，王文薇，刘 浩，陆 卓，尹作为. 一种特殊条带南红玛瑙的拉曼光谱分析[J]. 光谱学与光谱分析, 2021, 41(04): 1271-1275.
GUO Mei, WANG Wen-wei, LIU Hao, LU Zhuo, YIN Zuo-wei. Raman Spectral Analysis on a Special Band of Nanhong Agate. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(04): 1271-1275.
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