摘要
寿山石品种繁多,其鉴别和分类也一直是个难题。首次利用便携式近红外光谱仪(NIR)研究了不同类别寿山石的近红外光谱特征。根据寿山石样品状态(块状和粉末状)的不同表面形态、粒度、质量等因素对近红外光谱测试结果的影响进行了分析,讨论了近红外光谱的主要吸收峰归属,旨在探索一种无损、便捷的寿山石鉴别方法。结果表明,利用便携式近红外光谱仪完全可以区分寿山石的三个主要类别,即高山石类(高岭石族)、芙蓉石类(叶蜡石)、汶洋石类(伊利石)。在块状寿山石样品的近红外光谱1400nm区域,高岭石族矿物表现为一对双峰;叶蜡石和伊利石都仅有一特征单峰,叶蜡石表现为1392nm,伊利石表现为1406nm。寿山石样品的表面形态对近红外光谱没有明显的影响。粉末状寿山石样品的近红外光谱吸收峰更为尖锐,分裂程度更好。除了1400nm处的吸收峰外,在2180nm左右,高岭石类矿物表现为双峰,而叶蜡石和伊利石为单峰,但叶蜡石的吸收峰位于2168nm,伊利石位于2195nm。在条件允许的情况下,获取10mg左右的寿山石样品粉末,便可获得清晰的近红外光谱。
Due to numerous larderites in the market, it is of a great challenge to identify the genuine ones from the fake ones, not to mention classifying them. However, near infrared spectroscopy（NIR）, a new technology to identify larderite, is applied firstly to study the near infrared spectrum characteristics of larderites. In order to obtain sufficient data, the blocky and powdered larderites were respectively tested in several conditions, including dif- ferent surface morphology, particle size and weight. And the experimental data show that NIR is capable of identifying and classifying larderites mainly based on the differences around 1 400 nm, and it is in a more efficient and non-destructive way than XRD does. More specif- ically, spectra of kaolin-group minerals witness a double peak around 1 400 nm. By contrast, spectra of pyrophyllite and illite show a single peak, respectively at 1 392 nm and 1 406 nm. Apart from the 1 400 nm region, another area around 2 180 nm exhibits distinguishable fea- tures of three types of minerals. Also, a corresponding double-peak can be recognized fromthe spectra of kaolin-group minerals when samples are grinded into powder, while no peak exhibits in the spectra of blocky sample. In contrast, pyrophyllite, as well as illite, exhibits a single peak in this region. More importantly, the peak positions of pyrophyllite and illite are fundamentally different, respectively at 2 168 nm and 2 195 nm, which could be used to distinguish pyrophyllite from illite. Additionally, spectral resolution of powdered larderites is much higher than that of blocky samples, which means that the spectrum of the powdered larderites is more accurate than that of blocky ones. In general, by comparing the spectra of minerals in different weight, it is proved that 10 mg powdered sample is optimum to obtain their valid and accurate near infrared spectra, meanwhile decreasing damage to a maximum degree.
出处
《宝石和宝石学杂志》
CAS
2014年第5期34-43,共10页
Journal of Gems & Gemmology
基金
福州百年景福堂珠宝有限公司的资助
关键词
寿山石
近红外光谱
鉴别
larderite
near infrared spectroscopy
identification
