多米尼加与墨西哥蓝珀光致发光-拉曼光谱及微量元素赋存特征研究

Characteristics of Photoluminescence and Raman Spectra, and the Occurrence of Trace Elements of Blue Amber from Dominican Republic and Mexico

蓝珀主要产于多米尼加共和国、墨西哥与缅甸,其形成机制、组成成分及光谱特征与之特定的产出地理环境有密切的关联。因此,蓝珀的产地研究成为当前珠宝玉石、考古及生物矿物学研究领域的热点课题。前人主要应用红外光谱、X射线荧光光谱、质谱、同位素示踪等技术开展了较系统的蓝珀产地的溯源研究,但限于蓝珀材质的类同,不同产地蓝珀的光谱学等特征存在相似性。同时,因部分检测设备应用的普及性不高,因此给基于上述相应设备所关联的检测方法的应用带来了较大局限。本文应用光致发光(Photoluminescence, PL)与拉曼光谱结合微量元素分析对多米尼加共和国与墨西哥两个不同产地蓝珀的光谱与元素赋存特征予以研究。结果表明:(1)室温下,在以405nm为激发波长的PL光谱中,多米尼加蓝珀同时出现约450、475与502nm处峰位。相比之下,墨西哥蓝珀未见明显特征峰,以上两产地蓝珀的PL光谱差异性可作为其产地溯源鉴定的直接依据。(2)在以785nm为激发波长的拉曼光谱中,多米尼加蓝珀在约154、468、901、1177及1312cm^(-1)处的拉曼峰较墨西哥蓝珀在上述位置处的峰位更为明显。同时,多米尼加蓝珀对应的谱图中约1653cm^(-1)与1446cm^(-1)处峰强比值N(N=I_(1653)/I_(1446))明显高于墨西哥蓝珀的上述峰位比值;(3)两个产地蓝珀中均含有微量的S、Si、Fe与Cu,且含量大小均呈现S>Si>Fe>Cu特征。相比之下,多米尼加蓝珀中Cu元素一般高于墨西哥蓝珀,因此Cu赋存含量特征可作为多米尼加蓝珀溯源的佐证依据之一。

BACKGROUND: Blue amber is mainly produced in the Dominican Republic, Mexico and Myanmar. Generally speaking, the formation mechanism, composition and spectral characteristics of blue amber are closely related to its specific geographical environment. Therefore, the study on the origin of blue amber has become a hot topic in the field of gemology, archaeology and biological mineralogy, and the origin of geographical districts of blue amber has become a hot research topic. Previous studies mainly used infrared spectroscopy, X-ray fluorescence spectroscopy, mass spectrometry, and isotope tracing to carry out a relatively systematic study on the origin of blue amber, but were limited to the similarity of blue amber, and the spectral characteristics of blue amber from different origins showing similarities. Due to the low popularity of the application of some detection devices, the application of the detection method based on the above-mentioned corresponding devices is greatly limited.OBJECTIVES: To identify photoluminescence(PL), Raman spectroscopy and trace element characteristics of blue amber with different origins.METHODS: Photoluminescence and Raman spectroscopy combined with trace element analysis were used to study the spectral and elemental occurrence characteristics of blue amber from Dominican Republic and Mexico.RESULTS: The results showed that:(1)At room temperature, using PL spectrum with 405 nm as the excitation wavelength, the peaks at 450, 475 and 502 nm appeared simultaneously for blue amber from Dominican Republic. In contrast, there was no significant characteristic peak in Mexican blue amber. The differences in PL spectrum of blue amber from the two origins can be used as a direct basis for the traceability and identification of its origin.(2)Using the Raman spectrum with 785 nm as the excitation wavelength, the Raman peaks of blue amber from Dominican Republic at about 154, 468, 901, 1177 and 1312 cm^(-1)were more prominent or sharper than those from Mexico. The ratio of the peak intensity at 1653 and 1446 cm^(-1)(N=I_(1653)/I_(1446)) in the corresponding spectrum of the amber from Dominican Republic was significantly higher than that from Mexico.(3)Trace elements of S, Si, Fe and Cu were present in the blue amber from the two regions, and the content was S>Si>Fe>Cu. The content of Cu in blue amber from Dominican Republic was generally higher than that from Mexico. Therefore, the occurrence and content characteristics of Cu can be used as one of the evidences for the traceability of Dominican blue amber. CONCLUSIONS: The research work provides theoretical and technical support for the origin of blue amber with different geographical locations. It can also provide a salutary reference for identification of the geographical location for other gems.