新疆若羌阿其克库勒碧玉的宝石学特征研究

通过常规宝石学测试、偏反光显微镜鉴定及电子探针、X射线粉晶衍射测试分析,对产于若羌县阿其克库勒的碧玉进行详细研究,总结其产地特征及成因。结果表明碧玉主要矿物成分为透闪石并含少量钙铬榴石、铬铁矿。透闪石在偏光显微镜下呈鳞片状、片状、纤维状,其中片状具轻微卷曲变形现象,偶见少量辉石为原岩蚀变残留矿物。钙铬榴石为翠绿色,呈针点状、斑点状、团块状、丝绺状不均匀分布,铬铁矿呈黑色,以点状、不规则粒状杂乱分布。铬铁矿由铬镁尖晶石蚀变形成,蚀变程度不一,可见铬铁矿沿铬镁尖晶石边缘分布。碧玉的绿色源于Fe^2+和Cr^3+综合作用形成,结合铬铁矿与碧玉成因及产状特征,推断该种碧玉为超基性岩蚀变形成,与新疆和田碧玉、玛纳斯碧玉、俄罗斯碧玉、新西兰碧玉、加拿大碧玉等属于同一成因类型。

Research on Gemological Characteristics of Jasper in Ruoqiang Aqikekule of Xinjiang

The jasper produced in ruoqiang county is the first reported,Through conventional gemology test,partial re- flection microscopy,electron probe and X-ray powder diffraction analysis,the jasper from ruoqiang aqikekule was re- searched in detail and Summarized its origin characteristics and causes.The results show that the main mineral composi- tion of jasper is tremolite with a small amount of uvarovite and chromite.The amphibole was scaly,flaky and fibrous un- der polarizing microscope,with slight crimp deformation,Occasionally a small amount of pyroxene is residual mineral of original rock alteration.The uvarovite is emerald green with uneven distribution of needlelike,speckled,lumpy and wire- grain,Chromite is black and distributed in point and irregular granular disorder.Chromite formed by the alteration of Chrome-magnesium spinel with varying degrees of alteration.,It can be seen that chromite is distributed along the edge of Chrome-magnesium spinel.The green color of jasper originated from the synthesis of Fe^2+and Cr^3+,and based on the gene- sis and occurrence characteristics of chromite and jasper, it is inferred that this kind of jasper is formed by superbasic rock alteration.It belongs to the same genetic type as hetian jasper,manas jasper,Russia jasper,New Zealand jasper and Canada jasper.