华阳川地区天河石矿物学特征研究  

Mineralogical characteristics of amazonite in Huayangchuan area

作　　者：杨蓉[1] 胡海燕 张丽倩[1] YANG Rong;HU Hai-yan;ZHANG Li-qian(School of Jewellery,Shaanxi Institude of Interational trade&Commerce,Xi’an 712046)

机构地区：[1]陕西国际商贸学院

出　　处：《矿产勘查》2019年第9期2280-2285,共6页Mineral Exploration

基　　金：陕西国际商贸学院校级科研项目(编号:SMXY201814)资助

摘　　要：位于华北克拉通南缘小秦岭地区的华阳川发育含天河石伟晶岩,其中的天河石蓝绿色-绿色,半透明-微透明,玻璃光泽,表面可见一组平行解理,自形板柱状居多,少数为不规则块状,粒度(0.6~2)cm×(2.5~4)cm,最大可达2cm×6cm。晶面上可见白色平行排列的条纹。天河石镜下以条纹长石状态存在,形态上呈细脉状,主晶手标本显示蓝绿色,单偏光下无色透明,负低凸起,正交镜下呈一级灰色,无多色性,内部发育交织规则的、明暗相间的格子双晶,宽度较大,一般可达100~150μm。电子探针(EPMA)结果显示,该部分的化学成分主要为SiO2(平均63.306%),Al2O3(平均17.456%)以及K2O(平均16.360%),指示其矿物成分为钾长石为主。嵌晶手标本显示白色,单偏光下呈无色透明,负低凸起,正交镜下呈一级灰干涉色,无多色性,宽度一般为40~80μm,内部双晶不发育。主晶与嵌晶延长方向相同,各自具有一致的光性方位,正交光下各自同时消光,电子探针(EPMA)结果显示,其化学成分为SiO2(平均68.009%),Al2O3(平均18.746%)以及Na2O(平均10.819%),分析化学成分可得其矿物成分上以钠长石为主,含少量的钾长石(0.4%~0.7%)和钙长石(0.4%~2.0%),镜下特征以及电子探针结果指示其为钠长石(NaAlSi3O8)。华阳川伟晶岩中的天河石中钾长石与钠长石分异作用较强,说明其形成温度较低,使钠长石从熔体中大量晶出。Amazonite-bearing pegmatites are developed in Hanyangchuan,who is located in Xiaoqinling area of southern margin of North China craton.The Amazonites are blue-green,translucent-transparent and glassy.A group of parallel cleavages can be seen on the surface.Most of them are self-shaped plates and columnar,a few are irregular blockss,with a particle size of 0.6-2 cm*2.5-4 cm and a maximum of 2 cm*6 cm.White parallel stripes can be seen on the crystal plane.Perthite as striped Feldspar under the microscope,which is veinlet in shape.The main crystal hand specimen shows blue-green color,transparent under single polarization light,negative low protrusion.Under the orthogonal mirror,it is gray and non-polychromatic.There are regular interlaced twin lattice crystals with light and dark in the interior.The width of the twin lattice crystals is larger,generally up to 100-150μm.The results of electron microprobe(EPMA)showed that the chemical composition of this part was mainly SiO2(average 63.306%),Al2O3(average17.456%)and KO2(average 16.360%),indicating that its mineral composition was mainly potassium feldspar.Embedded hand specimens showed white,transparent and colorless under single polarized light,negative low protrusion,first-order grey interference color under orthogonal mirror,non-polychromatic,width is generally 40-80μm,internal twin crystal is not developed.The main crystals and the inlay crystals have the same direction of extension,and have the same optical orientation.They are extinct simultaneously under orthogonal light.The results of electron microprobe(EPMA)show that their chemical compositions are SiO2(average 68.009%),AlO2(average 18.746%)and NaO2(average 10.819%).The mineral composition of albite can be obtained by analyzing the chemical compositions.The main minerals are potassium feldspar(0.4-0.7%)and calciferous feldspar(0.4-2.0%).Microscopic characteristics and EPMA results indicate that they are albite(NaAlSi3O8).Potassium feldspar and albite in Tianheshi of Huayangchuan pegmatite are strongly dif

关 键 词：华阳川 天河石 岩相学 电子探针 

分 类 号：P57[天文地球—矿物学]