摘要
富锶文石是文石的变种,其化学式为(Ca,Sr)CO3。二轴晶,负光性,2▽=9,折光率Ng=1.6620,Nm=1.6561,Np=1.5168,D=3.34,H=3.75,比磁化系数为0.32×10-6CGSMcm3/g。矿物为白色,透明,呈细小晶粒状或砂糖状集合体。易溶于稀盐酸。斜方晶系,晶胞参数a=4.61,b=7.89,c=5.78。矿物产于内蒙古白云鄂博铁、铌、稀土矿床的脉状含铌、稀土白云石碳酸盐岩中,在自然界中产出含锶如此之高的变种是罕见的。该矿物的发现对研究碳酸盐矿物中钙、锶元素类质同象置换机理和晶体光学均具有一定的学术意义。
The strontianiferous aragonite reported in the present paper is an aragonitic variety found in Bayan Obo iron ore deposit, Inner Mongolia. It occurs in veined Nb-, REE-bearing dolomite carbonatite and is mainly associated with dolomite, ankerite, monazite, carbocernaite, pyrochlore, norsethite, calcite, calciostrontianite, benstonite, zircon, apatite, phlogopite and albite.Strontianiferous aragonite is similar in chemical composition and crystal texture to aragonite. It acquires this name simply on account of its chemical composition and crystal texture.The mineral occurs as a fine-grained aggregate with individual crystal 0.01-0.03mm in diameter, transparent, white in color, luster vitreous,streak white, D=3.34, H(vicies)= 180- 190kg/mm^2 (=3.8Mohe), K=0.32×10^(-6)C.G.S.M.cm^3/gram.In transmitted light the mineral is transparent and colorless, cleavage no or very imperfect. It is biaxial negative with 2V= 9°, Ng=1.6620, Nm=1.6561, Np=1.5168.X-ray investigation shows that the mineral is orthorhombic, with unit cell values being α=4.91, b=7.89and c=5.78.The strongest X-ray spacings are 5.39(5), 3.456(10), 3.354(8), 3.773(7), 2.398(7), 2.016(9), 1.864(9).Chemical analysis yields the formula of (Ca_(0.4964)Sr_(0.4445)Mg_(0.0114)Ba_(0.0171)Al_(0.0007)Fe_(0.0038)K_(0.0009)Na_(0.0063)Mn_(0.0016)REE_(0.0066))_(0.9892)[(CO_3)_(0.9973)(OH)_(0.0308)]_(1.0281) with the brief form being (Ca, Sr)CO_3. Its DTA curve and infra-red spectrum are similar to those of aragonite.
出处
《岩石矿物学杂志》
CAS
CSCD
1990年第1期79-84,T005,共7页
Acta Petrologica et Mineralogica
