摘要
本文通过微观结构表征研究了澳大利亚、埃塞俄比亚、墨西哥三个产地欧泊的结构特征,揭示了不同产地欧泊变彩效应的形成机制,为欧泊的产地鉴别提供了科学依据。通过常规宝石学仪器检测和红外光谱测试对三个产地欧泊宝石学特征及分子振动光谱特征进行对比,再通过扫描电镜测试观察微观形貌特征,解释不同变彩颜色形成原因。可知欧泊的内部结构为二氧化硅小球三维堆积而成,其变彩效应与二氧化硅球体的粒径大小密切相关。澳大利亚欧泊的二氧化硅球体呈现高度规则排列,粒径分布范围为110~330nm,符合立方紧密堆积结构,部分球体在投影面上呈现六边形对称,这种有序结构导致其产生多色且绚丽的鳞片状变彩效应;埃塞俄比亚欧泊的二氧化硅球体粒径为12.5~60nm。排列较为致密但缺乏长程有序性,而局部区域的球体团聚可形成三维光栅结构,从而产生变彩现象;墨西哥欧泊仅由近似球形的纳米颗粒组成,平均粒径约30nm,未观察到典型的二氧化硅球体紧密排列结构,无变彩效应。
This study investigates the structural characteristics of opals from three distinct origins-Australia,Ethiopia,and Mexico-through microstructural characterization,elucidating the formation mechanisms of the play-of-color in opals from these regions and providing a scientific basis for origin identification.By employing conventional gemological instruments and infrared spectroscopy,the gemological features and molecular vibrational spectra of opals from these three origins were compared.Additionally,scanning electron microscopy(SEM)was utilized to observe the micro-morphological features,explaining the causes of the different play-of-color effects.The internal structure of opals is composed of three-dimensional stacking of silica spheres,and the play-of-color effect is closely related to the size of these silica spheres.In Australian opals,the silica spheres exhibit a highly ordered arrangement with a size distribution ranging from 110 to 330 nm,conforming to a cubic close-packed structure.Some spheres display hexagonal symmetry in projection,resulting in a multi-colored and vibrant scaly play-of-color effect.Ethiopian opals,on the other hand,have silica spheres with sizes ranging from 12.5 to 60 nm.These spheres are densely packed but lack long-range order.However,localized clustering of spheres can form three-dimensional grating structures,leading to the play-of-color phenomenon.In contrast,Mexican opals consist of approximately spherical nanoparticles with an average size of about 30 nm.No typical close-packed structure of silica spheres is observed,and as a result,these opals do not exhibit a play-of-color effect.This research highlights the critical role of silica sphere size and arrangement in determining the optical properties of opals,offering valuable insights for gemological identification and classification.
作者
尹焕秋
赵俊
YIN Huanqiu;ZHAO Jun(Guilin University of Technology,Guilin 541004;Baoshan University,Baoshan 678000)
出处
《中国宝玉石》
2025年第2期23-30,共8页
China Gems & Jades
关键词
欧泊
结构
变彩成因
扫描电镜
opal
structure
play-of-color mechanism
scanning electron microscopy
