墨西哥红蓝料琥珀的宝石学及谱学特征

Gemological and Spectral Characteristics of Mexican Red Blue Amber

近年来,墨西哥蓝珀备受欢迎,在市场上占有量越来越大。红蓝料琥珀作为蓝珀的品种之一,因其表层通常具有一层褐红色的氧化皮层,内层琥珀在紫外光下具有蓝绿色荧光,被称为“红皮蓝珀”。但墨西哥琥珀中的红蓝料由于形成条件的限制非常稀少。通过宝石学常规测试、显微放大观察、傅里叶红外光谱和光致发光光谱等,对墨西哥红蓝料琥珀的宝石学特征和谱学特征进行研究,并与墨西哥的黑皮料琥珀展开对比研究。墨西哥红蓝料琥珀红皮常呈微透明,内部为半透明—微透明,红皮厚度不均,由黑色点状包裹聚集流动组成。长波紫外灯下红皮部分显示弱至无的荧光,内部显示较强的蓝色荧光。红外光谱中墨西哥红蓝料红皮部分位于1723和1233~1046 cm^(-1)处的吸收峰分别是由含氧基团C O及C—O所致,由—CH_(3)所致的吸收峰位于2928 cm^(-1),其中含氧基团C O是使红蓝料琥珀呈现红色的生色团。红蓝料琥珀红皮部分C O峰与—CH_(3)峰的吸收强度比约为4/5,而内部约为2/5~1/2,红蓝料琥珀表层红皮部分的氧化程度较内部强,并且红蓝料琥珀内部氧化程度高于黑皮料内部。光致发光光谱结果表明红蓝料琥珀的红皮部分和内层的发光中心不同,红皮部分以562和506 nm为发光中心,而内层大多以467和472 nm为发光中心。随着氧化程度的增加,发光中心逐渐红移,荧光强度明显降低,C O对墨西哥红蓝料琥珀的荧光起到了淬灭作用。黑皮料琥珀内部特征谱峰具489和466 nm两个宽的发光中心,黑皮料琥珀内部的荧光强度较红蓝料琥珀更高。该研究为墨西哥红蓝料琥珀的鉴别提供了依据,有助于墨西哥红蓝料琥珀与其他产地、其他品种琥珀的区分,具有重要的理论意义和市场运用价值。

In recent years,Mexican blue amber has become popular and has an increasing market share.Red blue amber is one of the varieties of blue amber,it usually has a maroon oxide surface layer,and the inner amber has blue-green fluorescence under ultraviolet light,so it’s also called“red skin blue amber”.However,the red blue materials in Mexican amber are very scarce due to the limitation of the formation conditions.In this research,gemological characteristics and spectral characteristics of Mexican red blue amber were studied using gemological routine methods,microscopic observation,infrared spectroscopy and photoluminescence spectroscopy Mexican black skin amber was investigated as a comparison with red blue amber.The red skin of Mexican red and blue amber is often slightly transparent,and its interior is translucent to slightly transparent.The thickness of red skin is uneven,and it is composed of black dots wrapped and flowing.The red part shows weak to no fluorescence under long-wave ultraviolet,and the inside shows strong blue fluorescence.The FTIR absorption peaks at 1723 and 1233~1046 cm^(-1)in the red part of the red blue amber are respectively caused by oxygen-containing groups C O and C—O.The absorption peak caused by—CH_(3)is located at 2928 cm^(-1).The oxygen-containing group C O is the chromophore that makes red blue amber appears red.The absorption intensity ratio of the C O peak and—CH_(3)peak of the red blue amber red part is about 4/5,and the inner part is about 2/5~1/2.The oxidation degree of the red part of red blue amber is stronger than the inner part,while the oxidation degree of red blue amber’s inside is higher than that of the black skin amber’s inside.Photoluminescence spectroscopy results show that the red part of red blue amber has different luminescence centers with the inner part.The luminescence centers of red part are located at 562 and 506 nm,while the inner part mostly emits 467 and 472 nm center.As the degree of oxidation increases,the luminescent center gradually shifts to red spectra region,and the fluorescence intensity is significantly decreases.C O quenches the fluorescence of Mexican red blue amber.The inner part of the black skin amber has two wide luminescence centers of 489 and 466 nm.The fluorescence intensity of black skin amber inside is higher than that of red blue amber inside.This research provides a basis for the identification of Mexican red blue amber and is beneficial for readers to distinguish Mexican red blue amber from other origins and other varieties.It has important theoretical significance and market application value.