墨玉及处理“墨玉”的鉴定特征

Identification Characteristic of Mo Yu and Treated“Mo Yu”

采集我国南阳玉石市场上据称产自广西等西南地区的两类外观相似、但宝石学特征不完全相同的“墨玉”样品,对其进行常规宝石学测试,以及红外光谱、X射线荧光光谱、X射线粉末衍射、拉曼光谱等测试。对比分析得出,两类样品均以透闪石为主,有一类样品含有石墨矿物,质地比较细腻。造成其黑色外观的原因之一为天然形成,放大观察基底为白色或灰白色,石墨矿物分散其中,根据国家标准定名软玉或和田玉,可归属于墨玉;另一类样品为人工处理致色,具体方法未知,处理后样品外观虽然肉眼观察为黑色,但放大观察基底呈褐色,并且具弱的荧光现象,在拉曼光谱中无法测得主矿物峰位,与天然样品不同,根据国家标准可定名软玉(处理)或和田玉(处理),不能定名墨玉。

Two types of“Mo Yu”samples with similar appearance but different gemmological characteristics were collected from Nanyang jade market,and the samples are reportedly deposited from Guangxi Province and other southwest regions in China.Through conventional gemmological tests,as well as other tests using Infrared spectrometer,X-ray fluorescence spectrometer,X-ray powder diffractometer,Raman spectrometer etc.It is found that both types of samples are mainly composed of tremolite,one type of which contains graphite minerals,and the samples’textures are relatively fine.One of the reasons for the black appearance is natural formation,and the base colour is white or grayish white when the samples are viewed under microscope,as tiny graphite minerals can be seen scattering in the samples.According to the national standards,it should be named Nephrite or Hetian Jade,and belongs to the category of Mo Yu.The other type is caused by artificial treatment,and the specific method is unknown.Although by naked eye,the treated samples also have black appearance,but when magnified,it shows brown base colour.The fluorescence phenomenon of treated samples is weak,and the peak of tremolite cannot be observed in Raman spectrum.Different from the natural samples,it can be named nephrite(treated)or Hetian Jade(treated)according to the national standards,but can not be named as Mo Yu.