An Analysis of Characteristics of “Water Line” in Nephrite from Qinghai Province
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摘要: “水线”是青海软玉的重要特征，分析青海软玉“水线”的结构特征，为进一步研究“水线”的地质成因及鉴别软玉的产地具有十分重要的意义。通过显微薄片，扫描电子显微镜观察及电子探针测试等方法对青海软玉“水线”的结构特征及矿物组成进行系统分析。结果显示，“水线”处的矿物组成均为透闪石。在偏光显微镜下，根据“水线”处的颗粒与主体矿物颗粒的相对大小和排列有序度，将青海软玉“水线”分为三种类型：“水线”处的颗粒较主体矿物颗粒的粗大，长约25μm，宽约4μm，排列杂乱；“水线”处的颗粒近平行排列，长为10～20μm，宽约2μm，与边界呈近90°夹角；“水线”处的颗粒细小，长约10μm，宽在0.5～1.0μm之间，边界清晰。扫描电子显微镜的测试结果显示，“水线”处的透闪石呈长纤维状平行排列，并有针状、粒状透闪石颗粒穿插其间，总体定向性优于主体矿物的。Abstract: The“water line”in nephrite from Qinghai Province is one of its most important characteristics.Analyzing the structure characteristics of“water line”in nephrite from Qinghai Province is very important for further research on the geological origin of“water line”and identification of the origin of nephrite.The structure characteristics and mineral composition of“water line”in nephrite from Qinghai Province are systematically analyzed by using the polarizing microscope，ESEM and EPMA.The results show that the mineral composition in the“water line”is tremolite.The“water line”in nephrite from Qinghai Province can be classified into the following three categories according to the size and order degree of arrangement of tremolite particles in the“water line”and in the subject mineral：the tremolite particles in the“water line”is bigger than those in the subject mineral，with a length of about 25μm and a width of about 4μm，and their arrangement is in a disorder；the tremolite particles in the“water line”are almost parallel to each other，with a length of 10－20μm and a width of about 2μm，meeting the boundary at an angle of nearly 90°；the tremolite particles in the“water line”are small，with a length of about 10μm and a width of 0.5－1.0 μm，and the boundary between the“water line”part and the subject mineral is very clear.ESEM results show that the tremolite particles，in a long fibrous form，are parallel to each other，in which there are a small amount of needle－like and granular tremolite particles.The orientation of the“water line”part is better than that of the subject mineral.
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Keywords:
- nephrite from Qinghai Province /
- “water line” /
- structure
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