钇易解石族的端员——钛钇易解石的发现  

THE DISCOVERY OF AN END MEMBER OF THE (Y)-AESCHYNITE GROUP-(TI,Y)-AESCHYNITE

作　　者：陈德潜[1] 尹道玲 周剑雄[1] 林兴源[1] 张汉卿[1] 施倪承[3] 

机构地区：[1]中国地质科学院矿床地质研究所 [2]地质矿产部江西省中心实验室 [3]中国地质大学

出　　处：《地质论评》1994年第1期82-86,共5页Geological Review

摘　　要：本矿物为新发现的钇易解石族的端员矿物——钛钇易解石,产于江西省龙南县足洞燕山期中粒白云母花岗岩及其风化壳中。矿物属斜方晶系,常呈板状或短柱状,为天然晶质体,浅黄色,粒度为0.075mm,硬度4.7,比重4.73,二轴正晶,Ng=2.248,Nm=2.212,Np=2.194,Ng-Np=0.054,2V=70°。空间群为D_(2h)^(16)-Pmnb,a_0=0.750nm,b_0=1.092nm,C_0=0.518nm,Z=4。主要化学成份为:TiO_2=55.15％,∑Y_2O_3=43.19％,不含结构水,化学式为(Y、∑Y)Ti_2O_6。(Ti,Y)-Aeschynite is an end-member mineral of the (Y)-aeschynite group, occurring in the Zhudong muscovite granite of Longnan county, Jiangxi province, China. It is orthorhombic, with a0 = 0.7348(6)nm, b0 = 1.0839(11)nm, c0 = 0.1534(4) nm and Z=4.Its space group is Pmnb.It is natural crystal, usually tabular in form. Color light yellow, streak white, luster strongly resinous, very fine (0.075 mm in diameter), H = 4.7, D = 4.4 (measured value) and 4.73 (calculated value). It is transparent under the microscope, showing parallel extinction and negative elongation; it is biaxial positive, with Ng≈2.248, Nm≈2.212, Np≈2.194, Ng-Np≈ 0.054 and 2V=70°.Its chemical compositions (%) is as follows: TiO2 = 55.15, Y2O3 = 30.32, Yb2O3= 4.07, Er2O3 = 3.49, Dy2O3 = 4.48, Gd2O3=0.83, Sm2O3 = 0.26, MnO = 0.01, FeO=0.03, SiO2 = 0.06, Al2O3 = 0.01, Nb2O5 = 0.01, Ta2O5 = 0. 04, CaO=0.01, ThO2 = 0.37, total = 99.14 (an average value for 6 analyses by JCXA-733 EMP). The empirical formula is calculated based on the structural formula ABaX6 as (Y0.78 Yb0.06 Er0.06 Dy0.06)0.96 Ti2O6, or (Y, ∑Y) Ti2O6.It occurs as an accessory mineral in granite. The associated minerals are do-verite, chernovite, gadolinite, xenotime, monzite, fergusonite and zircon. It usually intergrows with muscovite. Presumably, it is thought to be a product of auto-metasomatism (muscovitization) of granite, i. e. alteration of granite from biotite granite into muscovite granite.

关 键 词：钇易解石族 稀土元素矿床 花岗岩 

分 类 号：P618.440.4[天文地球—矿床学]