我国发现的一种新铀矿物——湘江铀矿

湘江铀矿产于湖南某地二迭系岩层中一铀矿床的氧化带中。对该铀矿床的成因目前有两种看法,一种认为是沉积变质型;另一种认为是沉积迭加热液型。湘江铀矿呈浅黄色的粉末状微晶集合体产于硅质岩的裂隙内或风化孔洞中。与铝铀云母,黄铁矿,石英,磷铝石等矿物共生。根据产地命名为湘江铀矿。

XIANGJIANGITE——A NEW URANIUM MINERAL DISCOVERED IN CHINA

Xiangjiangite named after the river, Xiangjiang (Hsiang River) occurs in the ixidized zone of a Permian uranium deposite as powdery microcrystalline aggregates: yellow to bright yellow with silky luster, hardness 1-2, specific gravity 2.9-3.1; readily dissolved in diluted HCL and H2SO4. It is nonfluorescent in short wave ultraviolet light.Under the microscope it appears light yellow, with Ng=1.593, Nm=1.576, Np-1.558, high interference colour, biaxial ( -), parallel as well as symmetrical extinction. Chemical analyses give UO3-56.24, Al2O3-0.90, Fe2O3-2.04, CaO-0.26, P2O5-8.15, SO3-5.65, H2O+-9.86, H2C--10.70, SiO2 (quartz)-4.42, As2O3-0.13 and in pyrite Fe-0.15, S-0.20, insol.-0.46, total 99.16. The idealized formula is: (Fe, Al)(UO2)4(PO4)2(SO4)2(OH) · 22H2OThe strongest X-ray power lines are 11.11(10), 5.58(8), 3.743(8), 3.313(8), 2.96(7), 4.621(6), 4.119(6), 2.179(5), 2.063(5). As determined by indexed powder data, optical data, electron diffraction patterns and by observing SED patterns of the fine crystal form with electron microscope, this mineral belongs to the pseudotetra-gonal system with a ≈ b7.17A, c = 22.22A, a/c = 3.10.The infrared absorption spectrum of the mineral studied includes five strong absorption bands at 264cm-1, 923cm-1, 1044cm-1, 1617cm-1, 3390cm-1, and three medium to strong absorption bands at 468cm-1, 534cm-1, 613cm-1.Differential thermal analysis study of Xiangjiangite shows four large endother-mic peaks at 95℃, 174℃, 330℃ on the DTA curve. There is a distinct weight loss on the DTG curve corresponding to the removal of H2O. In addition, an endothermic effect near 754℃ on the DAT curve may be related to the loss of SO2 and a smaller exothermic peak was observed near 990℃.