中途岛深水珊瑚的宝石学及谱学特征

Gemmological and Spectral Characteristics of Corallium sp.nov.from Midway Island

对12件产自太平洋中途岛附近海域水下约900~1500 m处深水珊瑚样品的宝石学特征和谱学特征采用常规宝石学测试、X射线粉末衍射仪、激光剥蚀电感耦合等离子体质谱仪、红外光谱仪、拉曼光谱仪、紫外-可见光谱仪等现代测试手段进行了系统研究,并对11件其他传统宝石级红珊瑚品种(阿卡珊瑚、莫莫珊瑚、沙丁珊瑚)样品进行了对比研究。结果表明,深水珊瑚与传统宝石级红珊瑚的常规宝石学特征和矿物组成基本一致,颜色通常以粉白色—橙粉色为主,并伴有不均匀分布的橘红色斑块。深水珊瑚的红外光谱显示位于1423、879、706 cm-1附近的吸收谱带,拉曼光谱特征峰主要出现在277、711、1086、1014、1127、1297、1518、2150、2255、2538、2640、3040、3374、3748 cm-1附近;紫外-可见光谱主要在283、313、493 nm和525 nm附近存在吸收峰,与传统宝石级红珊瑚品种的谱学特征基本一致。深水珊瑚的微量元素成分特征与传统宝石级红珊瑚存在一些差异,具有含Mg量低、含Ba量高的特点,以Mg/Ca、Ba/Ca比值为组元绘制二元图,可将深水珊瑚与其他传统宝石级红珊瑚品种区分开来。

12 pieces of Corallium sp.nov.were collected and studied by conventional gemmological testing methods and advanced instruments including XRD,LA-ICP-MS,FTIR,Raman spectrometer,and UV-Visible light spectrophotometer.A comparative study was conducted on 11 samples of traditional gem-quality coral species(such as Paracorallium japonicum,Corallium elatius and Corallium rubrum).The results showed the conventional gemmological characteristics and the mineral components of Corallium sp.nov.are almost the same as those of traditional gem-quality coral except that the colour of the Corallium sp.nov.is usually pale pink to salmon with uneven distribution of orange-red patches.The infrared spectra of Corallium sp.nov.showed the absorption peaks located near 1423,879,706 cm-1,while the Raman spectra mainly appeared in 277,711,1086,1014,1127,1297,1518,2150,2255,2538,2640,3040,3374,3748 cm-1,and the UV-Visible light spectra were mainly absorbed at 283,313,493 nm and 525 nm,which were basically consistent with the spectral characteristics of other traditional gem-quatity coral species.The trace elements content of Corallium sp.nov.is characterized by low Mg content and high Ba content.The binary diagram was drawn with Mg/Ca and Ba/Ca ratios as components,which can clearly distinguish Corallium sp.nov.from the other traditional gem-quality coral species.