鉴定热处理琥珀的关键证据

Critical Evidences for Identification of Heated Ambers

在琥珀热处理实验研究的基础上,采用常规宝石学方法和红外光谱仪,测试并跟踪收集和对比分析了实验样品热处理前、后的宝石学参数和红外光谱的变化规律及琥珀内含物的演化、改造与破坏标识,并对获得的琥珀热处理效果进行了成因分析,从而总结出鉴定琥珀热处理的关键证据。研究结果表明:(1)折射率的增加、荧光的弱化或湮灭是热处理琥珀的重要佐证;(2)盘状裂隙、红色流纹、汽化纹、龟裂纹和氧化裂纹是热处理琥珀的重要标识;(3)FTIR光谱中I=2930cm-1/I=1735cm-1比值若≤1,可视为热处理琥珀的红外光谱指纹检测依据;(4)1735,1700cm-1处的羰基(C?O)伸缩振动与1260～1156cm-1处的C—O伸缩振动吸收强度的明显增强及多峰合并的趋势反映出热处理琥珀表面的热氧化反应;C?O浓度的增加可能是热处理琥珀红色的生色团,同时又是热处理琥珀荧光的淬灭剂。

Based on the experimental study of the heat treatment of amber,the changes of the gemmological parameters and infrared spectra,and evolution,reworking and destroyed features of the inclusions in the amber samples before and after the heat treatment are tested and gathered and analysed by using the conventional gemmological methods and infrared spectrometer. The effect of the heat treatment of the amber samples are discussed on the origin,summing up some critical evidences for the identification of the heated ambers.The results indicate：（1）The increase of the refractive index,weakening and disappearing of the fluorescence are the important evidences for the heated amber;（2）Dish-shaped cracks,red lamina,evaporated cracks,tortoise-like cracks and oxidized cracks are the signatures for the heated ambers;（3）I=2 930 cm-1/I=1 735 cm-1≤1 in the infrared spectra is the fingerprint testing indicator for the heated amber;（4）Increase and combination of several peaks of carbonyl（C═O） oscillation at 1 735,1 700 cm-1and C—O oscillation at 1 260～1 156 cm-1represent the strong heat oxidization on the surfaces of the heated amber. The increase of carbonyl concentration is probably not only the reason to produce the red colour of the heated ambers,but also to curb fluorescence of the heated ambers.