角质型金珊瑚与黑珊瑚的宝石学特征研究

Study on Gemmological Characteristics of Horny Gold Coral and Black Coral

采用常规宝石鉴定方法、偏光显微镜、X射线荧光光谱仪、光栅光谱仪及红外光谱仪对未处理和覆膜处理的角质型金珊瑚、黑珊瑚样品的宝石学特征进行了测试研究。结果表明,该珊瑚样品的实测折射率为1.485～1.505,密度为1.336～1.349 g/cm3;其横截面呈同心环状结构,纵切面呈粗细不均的纤维结构,证明其横纵空间生长的机理;样品的主要化学成分为纯有机质,主要化学元素为I,次要的为Cl,Br,S和Ba,少量Si,Ca,Mg,Na以及微量元素Zn,Ti,Mn,Cu,V等,未出现Fe;耐酸蚀实验表明,样品在HCl和HNO3中不溶,在H2SO4中可缓慢溶解;样品的红外光谱具有3组弱—中—强特征吸收峰,表明其存在一系列氨基酸等有机成分。

The gemmological characteristics of the horny gold and black coral samples are studied by using the conventional testing methods, polarizing microscope, X-ray fluorescence spectrometer, grating spectrometer and infrared spectrometer. The results show that the refractive index of the samples is between 1. 485 and 1. 505, and the density is about 1. 336 1. 349 g/cm^3. The cross section of the samples is of concentric ring structure and the vertical section being uneven thickness fiber structure, which could prove the transverse and vertical growth mechanism of the horny gold and black corals. The main chemical composition of the coral samples is pure organic matter, the main element is I, secondary elements are Cl, Br, S and Ba,and a small amount of Si, Ca, Mg, Na with trace elements Zn,Ti, Mn,Cu and V （but no Fe）. The acid corrosion experiments show that the coral samples are insoluble in HCl and HNO3, and slowly dissolve in H2 SO4. The IR spectra of the samples are of weak -- moderate- strong characteristic absorption peaks, which prove the existence of organic in gredients such as amino acid.