陕西洛南秦紫玉矿床地质特征及找矿标志

Geological Features and Prospecting Signs of Qinziyu Deposit in Luonan County,Shaanxi Province

秦紫玉,又名“紫绿玛瑙”,为隐晶质石英质玉,以典型的“绿边红心”颜色环带独具特色,尤其是绿色系的石英质玉较为罕见,该玉石产自于陕西省洛南县北部山区。本玉石质地细腻,其颜色多为紫红色、绿色或白色,玻璃光泽,半透明―微透明,摩氏硬度约6.5~7.5,因资源稀缺受到市场追捧,很适合雕刻创作。原石呈团块状沿层理、劈理方向不均匀的分布于蓟县系巡检司组的彩色泥质板岩层中,通过地表路线追索、槽探揭露,结合深部钻探控制,发现秦紫玉矿体呈似层状,属沉积改造型矿床;研究对比发现,可利用地层标志、顶底板标志、构造标志等作为区域性找矿标志。

Qin Ziyu,also known as"purple green agate",is a cryptocrystalline quartz jade with a typical"green edge red heart"color band and unique characteristics.In particular,green series of quartz jade is rare.The jade comes from the mountains north of Luonan County in Shaanxi province.The jade is fine in texture,its color is purple-red,green or white,glass luster,translucent~slightly transparent,Morse hardness about 6.5~7.5.Due to scarce resources,it is highly sought after in the market and is very suitable for carving and creation;The original stone is distributed unevenly along the bedding and cleavage directions in the colored argillaceous slate in a block like manner,which is located in the top of Xunjiansi Formation.Through surface route tracing,trenching,and deep drilling control,it was found that the Qinziyu ore body is layered and belongs to a sedimentary modification type deposit;Through comparative research,it has been found that geological indicators,top and bottom plate indicators,alteration indicators,and structural indicators can be used as clear regional prospecting indicators.