光谱学与光谱分析, 2021, 41 (4): 1271, 网络出版: 2021-04-12  

一种特殊条带南红玛瑙的拉曼光谱分析

Raman Spectral Analysis on a Special Band of Nanhong Agate
作者单位
1 中国地质大学(武汉)珠宝学院, 湖北 武汉 430074
2 滇西应用技术大学珠宝学院, 云南 腾冲 679100
摘要
南红玛瑙是玛瑙中比较特殊的品种, 因其温润的质地和鲜艳的颜色被广大消费者接受。 云南保山南红玛瑙原石中常出现一种在外侧透明且与内侧分界明显的特殊条带, 在研究南红玛瑙时较少有提到这种条带。 采用显微激光拉曼光谱、 场发射扫描电镜来对此条带展开分析, 测试结果表明拉曼光谱中外侧(Ⅰ区)与内侧(Ⅱ区)区别在于503 cm-1峰的强弱变化和400 cm-1峰的分裂程度变化。 两个样品结果都显示503 cm-1峰强从外到内呈现逐渐减少直至消失以及400 cm-1峰在Ⅰ区和Ⅱ区规律性变化。 503 cm-1拉曼峰代表一种二氧化硅中间相矿物——斜硅石, 说明从外到内斜硅石的含量逐渐降低直至消失。 400 cm-1分裂峰396和402 cm-1的分裂程度随着503 cm-1峰强的减弱其分裂程度增强, 而400 cm-1的分裂程度差异反映玛瑙的结晶程度, 因此结晶程度与斜硅石的含量存在一定的相关性。 选取YND-6#2进行计算斜硅石的含量, 通过模拟I(503 cm-1)/ I(465 cm-1)峰强度比值与斜硅石含量的关系函数, 计算得到斜硅石含量最大值为11.67%, 表明其形成为非蒸发环境。 扫描电镜结果表明从Ⅰ区到Ⅱ区颗粒的尺寸增加、 排列的有序程度增加、 自形程度增加, 表明从Ⅰ区到Ⅱ区结晶程度增加, 综上得到南红玛瑙特殊条带内斜硅石含量的规律变化和结晶程度的变化以及Ⅰ区与Ⅱ区微观形貌差异和外观差异表明其为不同的生长阶段。
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 (section Ⅰ) 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.

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(4): 1271. GUO Mei, WANG Wen-wei, LIU Hao, LU Zhuo, YIN Zuo-wei. Raman Spectral Analysis on a Special Band of Nanhong Agate[J]. Spectroscopy and Spectral Analysis, 2021, 41(4): 1271.

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