青海软玉中“水线”的特征及其成因探讨

Study on Characteristics and Genesis of "Water Line" in Qinghai Nephrite Jade

通过X射线粉晶衍射分析确定了青海软玉中的“水线”主要由透闪石组成。扫描电镜下观察发现,“水线”部分中的透闪石纤维较软玉主体部分中的细且长(可达数mm),相互平行,与软玉主体部分中的透闪石纤维的大小及交织结构均存在明显差异。在显微镜下观察发现,“水线”部分中的透闪石纤维与软玉主体部分呈突变接触关系,纤维长轴方向与“水线”延伸方向近乎垂直。由此认为,青海软玉中的“水线”是由含矿流体沿软玉中的微裂隙充填形成,并据此认为,“水线”并非青海软玉所独有的产地鉴别特征。

The XRD analysis shows the “water line” in Qinghai nephrite jade is mainly composed of tremolite. The tremolite fibers in the “water line” part is thinner and longer （several ram） than that of tremolites in the nephrite part, and they parallel to each other. The tremolite fibers in the “water line” is in abrupt contact with the nephrite part. The arrange direction of the fibers is upright to the extend direction of the “water line”. The “water line” is formed by filling of ore fluid along cracks in nephrite jade. And the “water line” can not be regarded as the identification characteristic of its origin.