翡翠的成分和结构特征及其与种或地的关系

MINERAL COMPOSITIONS AND TEXTURES OF JADEITE JADE AND THEIR RELATIONSHIPS TO QUALITY TYPES

详细研究了 1 8块样品的成分和结构特征 ,最后总结了研究样品的结构和成分与种或地的关系。所研究的翡翠样品主要由硬玉和绿辉石组成 ,其次还有少量的长石和不透明矿物。主要的结构类型有粒状变晶结构 (粗粒状、中粒状、细粒状及微粒状 )、等粒变晶结构、不等粒变晶结构、柱状变晶结构、纤维状变晶结构、碎斑结构、交代结构、糜棱结构及碎裂结构等。翡翠的矿物成分和结构特征与其种或地存在着一定的对应关系 :透明度高的油青种、冰种经历了一定的后期地质作用的改造 ,如重结晶作用和交代作用 ,具有纤维状变晶结构和微粒状变晶结构等 ;透明度不太好的种经后期地质作用改造不明显 ,多具细粒状变晶结构和碎斑结构 ;而透明度差的豆种一般未经后期地质作用的改造 ,多具不等粒变晶结构、中粒状变晶结构、柱状变晶结构和碎裂结构等。所有具脉状、斑点状和团块状绿色的样品中 ,绿色部分的颗粒相对较细 ,多呈微粒状变晶结构或纤维状变晶结构。另一方面 ,在结构相似的条件下 ,矿物成分较单一的翡翠样品种相对较好 ,而含有其它矿物如长石及不透明矿物等的翡翠样品种相对较差。

The present paper studies 18 specimens in detail and summarizes the relationship of textures and minerals to the quality type. The jadeite jade specimens studied in the present paper are composed of main jadeite and omphacite (in only one specimen) and minor feldspar and some opaque minerals. These jadeite jade specimens show mainly following texture types: granular crystalloblastic texture, equigranular crystalloblastic texture, inequigranular crystalloblastic texture, prismatic crystalloblastic texture, fibrous crystalloblastic texture, mortar texture, mylonitic texture, fractured texture, and some textures formed by replacing. The quality of the studied jadeite jade specimens are closely related to the mineral compositions and textures. High quality jadeite jade specimens with high transparency, such as oily mass green jade and icy jade, were formed by later geological processes, such as recrystallization, or replacing, and show fibrous crystalloblastic texture, micro granular crystalloblastic texture. Moderate quality jadeite jade specimens have slightly been influenced by later geological processes, and often show fine granular crystalloblastic texture and mortar texture. The low quality jadeite jade specimens with low transparency, such as applegreen jade, have not been influenced by later geological processes, and mostly show inequigranular crystalloblastic texture, moderate granular crystalloblastic texture, prismatic crystalloblastic texture, and fractured texture. In all specimens with green veins, spots and masses, the green parts have micro granular texture of fibrous texture. On the other hand, if the texture is similar, the more pure the mineral composition of a jadeite jade specimen is, the higher the quality type of the jadeite jade specimen is. The jadeite jade specimens with other associated minerals, such as feldspar and some opaque minerals, are often poor in quality.