翡翠中共生矿物含量对翡翠定名的影响

Influence of Associated Minerals on Jadeite Naming

目前翡翠市场上出现了越来越多含共生矿物的翡翠品种,给翡翠定名带来了一定的困难。针对这一问题,选取了具有代表性的原石样品进行了研究。研究方法包括实测样品的相对密度,X-射线粉末衍射(XRD)物相量化分析,以及利用红外光谱观察共生矿物出现的机率。根据所含的共生矿物种类,翡翠可分为两类,一类为含钠长石的样品,另一类为含霞石和角闪石的样品。在反射光下,钠长石为透明玻璃状,而霞石呈磨砂玻璃状。基于上述鉴别特征,即可区分出钠长石和霞石。两类样品的相对密度都随共生矿物含量的增加逐渐降低,而理论密度值与实际测试密度值略有不同。结合上述研究结果以及岩石学命名规则,笔者探讨并提出了一套关于含共生矿物翡翠的命名规则。

More and more varieties of jadeite containing associated mineral deposits appear on market and bring difficulties in naming those jadeites. In order to solve this problem, the authors selected representative samples and conducted an investigation. Research methods include the relative density measurements of the samples and the quantitative analysis of X-ray powder diffraction （XRD）. Besides, infrared spectrum of different minerals is also used to estimate the intergrowth percentage of associated minerals. Concerning types of associated mineral deposits, there are two jadeites. One contains albite and the other contains nephe- line-amphibole. Under gemology microscope, albite and nepheline exhibit features of trans- parent glass and ground glass respectively, and this difference is typical in distinguishing al- bite and nepheline. The relative densities of both jadeites decrease with the increase of weight percentages of associated rdinerals, and the calculated densities show a slight difference with theoretical densities. Combining these results and naming rules of petrology, the authors propose a set of naming rules for the jadeites containing associated minerals.