明代播州杨氏墓出土冠饰上的蓝宝石矿料来源研究

目前国内出土了大量不同种类的明代彩色宝石文物,但绝大多数彩色宝石并不产自中国。为探讨播州杨氏墓出土的七凤三龙金冠上镶嵌的蓝宝石的矿料来源,本研究采用微量元素与内部包裹体特征相结合的方法对样品进行分析。通过激光剥蚀-电感耦合等离子体质谱法(LA-ICP-MS)分析样品的微量元素特征,发现样品的Fe、Ga含量较低、Mg含量较高以及Ga/Mg比值较低,以此得出样品为变质成因的蓝宝石,排除其产自岩浆成因矿床。观察样品的内部包裹体特征,并与不同变质成因蓝宝石产地样品的内部包裹体特征进行对比分析,得出该样品内部包裹体特征更类似于缅甸、马达加斯加蓝宝石。最后结合不同地区蓝宝石矿床发现、开采历史记载,综合研究分析得出,该件蓝宝石文物的矿料最可能来自于缅甸矿区。此项研究可为探索我国古代以蓝宝石为代表的彩色宝石类文物的产地研究提供一定科学依据。

Study on the provenance of a sapphire set in crown ornaments excavated from the Yang tomb in Bozhou of the Ming Dynasty

A large number of different kinds of colored gemstone artifacts of the Ming Dynasty have been unearthed in China, but the vast majority of colored gemstones did not originate in China. In our work, we analyzed a sapphire inlaid on a gold crown with seven phoenixes and three dragons excavated from the Yang tomb in Bozhou of the Ming Dynasty using an integrated study of trace elements and internal inclusion characteristics, in order to investigate the provenance of the sapphire. In situ analysis of trace elements by LA-ICP-MS reveals that the sample is characterized by low Fe and Ga contents and high Mg content with a low Ga/Mg ratio, which is consistent with the sapphire of metamorphic origin and excluded from magmatic origin deposits. The internal inclusions of the sample were observed and compared with those of other samples from different metamorphogenic sapphire provenances, and it was found that they were more similar to those of Myanmar and Madagascar sapphires. Finally, in combination with the historical records of the discovery and mining of sapphire deposits in different regions, the comprehensive research and analysis led to the conclusion that the ore for this sapphire artifact most likely came from the Myanmar mines. This study could provide some scientific basis for exploring the provenances of colored gemstone artifacts represented by sapphires of ancient China.