中国首次发现的水磷钙铀矿

Discovery of Tristramite in China

内蒙古二连盆地2082砂岩型铀矿床中的主要工业铀矿物为水磷钙铀矿(Tristramite)。该矿物在中国是首次发现。其矿物颗粒细小,与黄铁矿、白铁矿等硫化物、黑色炭屑紧密共生。颜色为灰黑色—黑色,不透明,反射光下呈灰色—暗灰色、均质、无内反射。13个电子探针分析数据得出的平均化学成分为UO241.60%,CaO 14.50%,P2O522.71%,SO31.33%,FeO 0.81%。按照除磷以外阳离子数和为1计算的经验化学式为:(Ca0.589U0.351Fe0.026Na0.016Al0.009Y0.007)0.998[(PO4)0.729(CO3)0.225(SO4)0.038(SiO4)0.008]1.00.1.75H2O。简化式可以写成(Ca,U4+,Fe)[(PO4)(CO3)].2H2O。通过X射线衍射数据,用SHELXTL PC进行晶胞参数精修得到的六方晶胞,其参数为a=b=(0.69030±0.00129)nm,c=(0.63300±0.00083)nm。

Tristramite is one of the main industrial uranium minerals from No.2082 sand-stone type uranium deposit located in Erlian basin of Inner Mongolia,China.It was discovered for the first time in China.This mineral is co-existence with black charcoal and sulfide such as pyrite,marcasite and so on.The optical properties of tristramite are gray black to black and non-transparent in transmitted light,but gray to dark gray,homogeneous,and without internal reflection in reflected light.The average chemical concentraitons of of UO 2 ,CaO,P2O5,SO3,and FeO from tristramite by 13 points analysis with EPMA are 41.60%,14.50%,22.71%,1.33%,and 0.81%,respectively.Based on the total cation number for 1 except that of phosphorus,the calculated empirical formula is （（Ca 0.589 U 0.351 Fe 0.026 Na 0.016 Al 0.009 Y 0.007） 0.998 [（PO4） 0.729 （CO3） 0.225 （SO4） 0.038 （SiO4） 0.008 ] 1.00 .1.75H 2 O,which can be simplified as （Ca,U4＋,Fe）[（PO4）（CO3）].2H2O.According to the X-ray diffraction data,the lattice parameter refinement result refined by SHELXTL PC indicates that tristramite belongs to hexagonal crystal system with the lattice parameters of a=b=0.69030±0.00129 nm and c=0.63300±0.00083 nm.