新发现的含铬浅闪石的矿物学研究  

The mineralogical study of a new Cr-bearing edenite variety

作　　者：吕林素[1] 尹继才[1] 

机构地区：[1]中国地质博物馆,北京100034

出　　处：《岩石矿物学杂志》2005年第3期231-238,共8页Acta Petrologica et Mineralogica

基　　金：中国地质调查局"地学专项挂图编制"项目资助 (2 0 0 3 13 0 0 0 0 49)

摘　　要：应用电子探针、X射线粉晶衍射和红外吸收光谱等分析手段对新发现的含铬浅闪石进行了系统研究,结果表明:其分子式为(Na0 .50 Ca0 .17K0 .0 6) 0 .73 Ca2 .0 0 (Mg3 .92 ⅥAl0 .79Cr3 + 0 .0 6Ti0 .0 4Fe2 + 0 .0 1Co0 .0 1) 4 .83 (Si6.54ⅣAl1.46) 8.0 0 O2 2 (OH) 2 ,简写为NaCa2 (Mg4Al)Si7AlO2 2 (OH) 2 ,晶胞常数为a =9.84 37(19) ,b =17.94 74 (37) ,c =5 .2 796 (15 ) ,β=10 5 .2 2 2 (17)°,V =90 4 .4 0 4 3 ,其结构中确实存在Ca原子占据A位以及Cr代Mg和Al代Si的情况,说明它为新的富钙富铬的闪石类矿物,并形成于贫硅富钙富铬的环境中,其翠绿色由铬所致,故名为含铬浅闪石。Based on such analytical methods as EMPA, XRD and IR, the authors extensively studied a new Cr-bearing edenite variety. The results show that the empirical formula of Cr-bearing edenite is (Na-(0.50) Ca-(0.17) K-(0.06))-(0.73) Ca-(2.00)(Mg-(3.92)()~ⅥAl-(0.79) Cr^(3+)-(0.06) Ti-(0.04) Fe^(2+)-(0.01)Co-(0.01))-(4.83)(Si-(6.54)()~ⅣAl-(1.46))-(8.00)O-(22)(OH)-2 according to revised IMA98 amphibole nomenclature, with the deal expression being NaCa-2(Mg-4Al)Si-7AlO-(22)(OH)-2. Its unit-cell parameters are a=9.843?7(19)?,b=17.947?4(37)?,c=5.279?6(15)?,β=105.222(17)°, V=904.404?~3 and Z=2. It has been discovered in its structure that Ca is at the A site, Mg is displaced by Cr and Si by Al. All this indicates that the studied mineral is a new chromic-calcic amphibole related closely to a Si-poor and Ca- and Cr-rich genetic environment. The name given to Cr-bearing edenite is based on the chemical composition and the special color caused by chromium.

关 键 词：矿物学 含铬浅闪石 角闪石族 

分 类 号：P578.955[天文地球—矿物学] P575[天文地球—地质学]