氟碳铈钡矿(Cebaite)的新资料

氟碳铈钡矿产于白云鄂博铁铌稀土矿床中。1965年发现于西矿区。贵阳地球化学所稀有矿物研究组(1972)和彭志忠、沈今川等(1980)及后来李方华等对该矿物进行了矿物学研究。本文报道了采自东矿区几个样品的分析测定结果。 一号氟碳铈钡矿(样品编号:东1606),产于东矿体靠近上盘的钠辉石型矿石中,与钠辉石、萤石、重晶石等矿物共生,矿物呈粒状或板状,大小不一,集合体大者直径可达数毫米。

NEW DATA FOR CEBAITE

Cebaite Ba₃Ce₂(CO₃)₅F₂ is a member of barium rare earth fluorocarbonate minerals, In the present paper three cebaite samples are studied by wet chemical analysis, optical microscopy, X-ray powder and single crystal diffraction analysis, measurement of infrared spectrum and differential thermal analysis.Cebaite is yellow to waxy-yellow in colour, luster vitroous to greasy. It is tabular of irregular form or anhedral grain in shape. Its cleavage is imperfect {301} and its specific gravity is determined by using a pycnometer. Density measurement are as follows: No. 1: 4.66 g/cm³, No. 2: 4.31 g/cm³, No. 3: 4.44 g/cm³. The theoretical density is 4.81g/cm³.Mohs hardness is 4.5-5.0. Optically, it is biaxial, negative, 2V small about 5°-10°, Ng -1.740-1.748, Nm-1.735, Np-1.598-1.604.Cebaite belongs to monocline system. Its parameters of elementary cell are: a₀ = 21.4256(Å), 60=5.0348(Å), c₀=13.2395(Å), β₀=94.613° V0=1423.57(Å)3, Z = 4. a₀: b₀:c₀ = 4.256:1:2.630. X-ray pattern of single crystal shows that cebaite has pseudo-structure and superstructure of crystal. X-ray powder diffraction data of cebaite are shown in Table 3.The results of wet chemical analysis for three cebaite samples are given in Table 1. The empirical formulae calculated on the basis of Ba + Sr + Ca+ Na + K = 3 are also given. The ideal formula will be Ba₃Re₂(CO₃)₅F₂. The theoretical composition gave(wt.%):BaO 44.65, Ce₂O₃ 31.86, CO₂ 21.36, F 3.68-0 = F₂ 1.55. The individual rare earth elements determined by wet chemical analysis show that in cebaite the cerium group of REE is predominant.Cebaite was discovered at Bayan-Obo, North China, in the early 1960s. The mineral as a new one was reported in the early 1970s. In this paper, the new data are obtained from three samples of cebaite collected from different places of East-mine of Bayan-Obo. The three cebaites are associted with aegirine, fluorite, barite etc., but the amounts of the associated minetals in each assemblage are quite different.