陕西洛南紫绿玛瑙宝石学特征

Gemmological Characteristic of Purple-Green Agate from Luonan,Shaanxi Province

陕西省洛南县境内近期发现了新的玛瑙玉石矿,该玉石以紫红色、红色、白色、绿色为主,偶见黄色 调、蓝色调,多呈玻璃光泽,与其他产地的石英质玉石宝石学参数基本相似.通过对该玉石样品的镜下观察,配合 XRD、激光拉曼、红外光谱、电子探针等大型仪器分析,确定其主要成分为石英,并含有少量的绿泥石、伊 利石、针铁矿、赤铁矿、方解石、白云石等杂质矿物.其中,针铁矿和赤铁矿是红色的主要致色矿物,绿泥石是 绿色的主要致色矿物.SEM观测结果显示,紫绿玛瑙主要由粒径较小（大多〈20μm）,且彼此间结合紧密的石 英颗粒组成,应属于隐晶质玛瑙的范畴.

A new agate ore was recently found in Luonan County, Shaanxi Province. The jade is mainly purple red, red, white and green, yellow and blue is seen occasionally, with vitreous luster. The gemmological parameters is similar to the quartz jade in other places. Through the jade sample was studied by using microscope, XRD, laser Raman, infrared spectroscopy, electron microprobe, etc. The main component of agate is quartz, with a small amount of impurity minerals such as chlorite, illite, goethite, hematite, calcite, dolomite, etc. Among the component, goethite and hematite are the main colour-causing mineral for red, and chlorite is main colour-causing mineral for green. SEM observation results showed that the purple green agate mainly consists of quartz particles that are smaller particle size （mostly less-than 20 ym） and closely combined with each other,should belong to the catego-ry of aphanitic jade agate.