缅甸翡翠中的长石矿物及其对翡翠质量的影响.doc

缅甸翡翠中的长石矿物及其对翡翠质量的影响 【中文摘要】世界上的翡翠产地有多个,其中只有缅甸的翡翠可以达到宝石级,被人们广泛的开采,加工。缅甸翡翠作为玉石是多种矿物的集合体。翡翠主要是以较纯净的硬玉矿物为主。近年来人们也将少量以绿辉石、钠铬辉石为主的玉石划回翡翠的范畴,对于这种划回方式,业内还存在争议。除了辉石质的主要矿物之外,翡翠的次要矿物主要是闪石和长石。缅甸翡翠中的长石矿物主要是钠长石。长石矿物特别是钠长石作为翡翠的常见次要矿物,与硬玉矿物之间存在着密切的关系。研究它们之间的关系对于弄清楚翡翠矿床的形成和翡翠原石赌石的评价有重要的意义。通过样品的常规宝石学测试,红外光谱测试,X粉晶衍射测试,电子探针分析,确定了缅甸的翡翠中确实含有一定数目的长石矿物。对长石矿物的晶体化学式的计算得出,这种矿物为钠长石;把X粉晶衍射的数据结果,代进斜长石形成条件的计算公式,得出该钠长石为低温钠长石。利用偏光显微镜下的薄片观察,发现翡翠中的钠长石矿物有两种存在方式一种是第一个世代钠长石,其形成的时间早于硬玉或同第一世代的硬玉矿物一起天生,另一种为后期热液作用形成的脉状的钠长石。通过对不同档次的翡翠中钠长石存在状况的比较,发现第一个世代的钠长石多出现在中低档次的翡翠中。综合两种产状的钠长石对翡翠的结构,透明度,颜色等诸多因素的影响,得出结论,钠长石的存在将会降低翡翠的质量。这个结论对翡翠原石的评价具有一定的意义。; 【Abstract】 Myanmar, out of many places producing feicui in the world, is the only one that can produce feicui achieving the level of gem and having been extensive mining and processing. Myanmar feicui, as a kind of jade, contains a variety of minerals. Feicui compose mainly by pure jadeite. In recent years, people tend to allocate a few jade composed by omphacite or ureyite under the scope of feicui. However, there are some arguments towards this classification within the industry. In addition to the principle pyroxene mineral, the secondary minerals of feicui are amphibole and feldspar. The major feldspar mineral in feicui is albite. As a common secondary mineral, feldspar minerals, especially albite, have shared a close relationship with jadeite minerals. Therefore, in order to make clear about the ation of feicui deposits and the uation of original feicui stone, it is highly worthwhile to have a close study on the relations between albite and jadeite minerals.Through samples of conventional gemological testing, IR tests, XRD testing as well as electron microprobe analysis, the feicui did contain a certain amount of feldspar minerals. By calculating the chemical ula of the mineral feldspar crystals, we have found that this mineral is albite. Furthermore, by using the data result of XRD, we are able to make out the calculating ula of the ing condition of long-ramp stone, thus getting the conclusion that this mineral should be cold albite.Using the thin slice observation under the polarized microscopy, we have found that there are two existential ways for albite minerals in emerald one is the first generation of albite which is earlier than jadeite or grows together with jadeite minerals; the other is albite of vein type which is ed by the hydrothermal fluid effect. By comparing the existing situation of albite in different grades of feicui, we have discovered that the first generation albites mainly appear in the low-level emerald. By synthesizing the influence of the two albite’s occurrence towards feicui’s structure, transparency, color and many other factors, we can reasonably get the conclusion that the existence of albite will reduce the quality of feicui. This conclusion will take on certain significance to the uation of original feicui stone.