湖北与安徽产高品质绿松石的红外与拉曼光谱特征及意义

近年来，市场对高品质绿松石的产地识别需求愈加迫切，然而，相应的研究尚少。湖北秦古、文峰和安徽笔架山产有结构致密细腻、光洁坚韧，蓝色的绿松石。它们的谱学特征基本一致，但在峰位或强度上存在可以识别的差异。红外光谱特征中，由δ(OH)弯曲振动引起的783 cm-1附近谱带在秦古样品中表现为797和779 cm-1分裂峰，在文峰样品中表现为787 cm-1峰，在笔架山样品中表现为783 cm-1峰。不同产地的R=I_{783 cm-1}/I_{837 cm-1}值不同，秦古样品R值在0.98以上，文峰样品R值在0.85左右，笔架山样品R值集中在0.91～0.94。属于ν₄(PO₄)伸缩振动内的609 cm-1附近谱带在文峰样品中较明显且强度大，在秦古样品中峰形略宽、强度稍弱，笔架山样品在该处吸收平缓且强度很小。拉曼光谱中在3 500 cm-1附近笔架山样品的峰位波数明显较湖北秦古和文峰样品的大(为3 506和3 505 cm-1)，而湖北所有样品的此峰均低于3 500 cm-1(3 495～3 500 cm-1)，可能由水组分的不同造成的，且其在3 472 cm-1附近的峰强度明显偏大。同样情况发生在由ν₄(PO₄)弯曲振动引起的551 cm-1峰，可能为微量元素Zn的含量差别所致。以上特征可作为识别湖北和安徽两产地绿松石的重要谱学标志，结合其外观特征，可以将二者有效区分。以上研究结果还具有潜在的考古学价值。

Infrared and Raman Spectra of High-Quality Turquoises from Hubei and Anhui,China: Characteristics and Significance

Recently, attentions has been paid to the origin of high-quality turquoise. However, few researches of spectroscopic characteristics of them have been performed to differentiate its original location. Although the general characteristics of spectra are resembled for Qingu, Wenfeng (Hubei province) and Bijiashan (Anhui province) turquoises, minute difference can be observed among them. Infrared spectra of the studied samples in this investigation show that peak near 783 cm-1 caused by OH bending vibration of turquoise from Qingu separates into two peaks, 797 and 779 cm-1. While the peak appears at 787 cm-1 for turquoises from Wenfeng and 783 cm-1 for the ones from Bijiashan. Intensity ratios of infrared absorption peaks at 783 and 837 cm-1(R=I_{783 cm-1}/I_{837 cm-1}) are different among them, more than 0.98 in samples from Qingu, 0.85 from Wenfeng and 0.93 from Bijianshan samples. Infrared band at 609 cm-1, which is related to the ν₄(PO₄) stretching vibrations, is quite obvious and sharp of Wenfeng samples, appears wider and less sharp of Qingu samples, while for Bijiashan sample, is the most plane. Peaks in Raman spectra around 3 500 cm-1 are different among the three locations, namely 3 506 and 3 505 cm-1 for samples from Bijiashan, 3 495 to 3 500 cm-1 for samples from Hubei province. Peak intensity around 3 472 cm-1 of turquoise from Bijiashan is larger than those from Hubei with the same situation occurring at peak ~551 cm-1. These findings, combining with appearance of the turquoises, can be used as important spectroscopic characteristics to recognize origins of the high-quality turquoises, which also have potential important implications in archaeology.