充填斜红磷铁矿的鉴别特征

Identification Characteristic of Filled Phosphosiderite

  • 摘要: 充填斜红磷铁矿是珠宝市场上常见的首饰材料,但目前对其充填物及充填程度的研究较少。采用常规宝石学测试、X射线粉末衍射、红外光谱、拉曼光谱、紫外-可见吸收光谱等方法对市场上常见的充填斜红磷铁矿样品进行了研究。常规宝石学测试表明,严重充填的斜红磷铁矿样品的充填区域光泽差异明显且荧光异常,但对于轻微充填的斜红磷铁矿样品,仅通过放大观察和荧光检查难以鉴别,需要进行详细的谱学测试。红外光谱测试结果显示,充填斜红磷铁矿样品在中红外区域可见1 510、1 250 cm-1谱峰,近红外区域可见5 985 cm-1谱峰,均与环氧树脂有关。拉曼光谱中,充填斜红磷铁矿样品不仅可见1 112、1 185、1 464 cm-1等环氧树脂组合峰,部分样品在裂隙处可见1 061、1 131、1 293、1 438 cm-1等与石蜡相关的拉曼峰。在紫外-可见吸收光谱中,充填斜红磷铁矿样品显示423、538、750 nm等处的吸收带,与天然斜红磷铁矿一致,说明充填物未对样品原本体色产生影响。市场上常见的斜红磷铁矿可能经过了多次充填加工流程,其内部充填物主要为无色或近无色的环氧树脂,通过红外光谱和拉曼光谱能够对其进行有效、无损的鉴别。

     

    Abstract: Filled phosphosiderite products are common in jewelry market, but the researches on fillings and filling degree are not enough.In order to provide more evidence for gem testing, different kinds of filled phosphosiderite samples from the jewelry market are investigated by conventional gemmological methods, X-ray diffraction, infrared spectra, Raman spectra and UV-Vis spectra.Results show that samples filled heavily can be identified by different luster and fluorescence.However, samples filled slightly, which are difficult to be identified by magnification and fluorescence, need more spectroscopy measurements.In the FTIR spectra, the absorption related to the epoxy resin fillings peaked at 1 510 cm-1 and 1 250 cm-1 in the medium-infrared region and 5 985 cm-1 in the near-infrared region are obvious.In the Raman spectra, the Raman shifts related to the epoxy resin at 1 112, 1 185 and 1 464 cm-1are consistent with the FTIR test results.Moreover, in the fissure of some samples, the Raman shifts at 1 061, 1 131, 1 293 and 1 438 cm-1 can be detected, which are due to the paraffin fillings.The UV-Vis spectra of the sample show the absorption bands at 423, 538 nm and 750 nm, which are in agreement with the untreated natural phosphosiderite.It can be inferred that the filling process has little effect on the original colour of the filled phosphosiderite samples.In a conclusion, the common filled phosphosiderite samples in jewelry market may undertake multiple filling processes, and the major fillings are colourless epoxy resin, which can be identified effectively and nondestructively by the FTIR and Raman spectra.

     

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