During the research on REE-bearing minerals from the Bayan Obo REE-Fe-Nb deposit, Inner Mongolia, China, ancylte was discovered in carbonatite at the eastern contact zone of the Bayan Obo deposit. It is the first time that this mineral ware distinguished and reported in Bayan Obo. Meanwhile, two subtypes of ancylite have been compositionally identified as ancylite-(Ce) and calcioancylite-(Ce), with chemical formulae: (Sr0.62 ,Ca0.18)0.8(Ce0.5 ,Nd0.36 ,La0.17 ,Pr0.02 ,Sm0.02)1.2(CO3)2(OH1,04 ,F0. 14)1.2H2O and (Ca0.73. Sr0.28, Ba0.17)1.2 (Ce0.46, Nd0.15, La0.15, Pr0.04 , Sm0.01 )0.8 ( CO3 )2 (OH0.75, F0.06 )o.8 H2 O, respectively. Both fomulas can be simplized as (Sr,Ca)2-x Ce,(CO3)2 · (OH,F)2-X · H2O, close to the ideal fomula (Sr,Ca)Ce (CO3)2(OH)H2O, but the latter contains OH~ and minor F-. The both are about severval to tens micrometers in sizes and occur as disseminated crystals only in late-stage calcite or intergrowth of calcite and dolomitite.%在对白云鄂博碳酸岩中稀土矿物的研究中,发现了锶-稀土含水复碳酸盐矿物.根据电子探针分析结果,其化学成分相当于碳锶铈矿(Ancylite-Ce)、钙碳锶铈矿(Calcioancylite),前者Sr＞Ca,后者Ca＞ Sr.计算得到的化学式分别为:(Sr0.62,Ca0.18)0 8(Ce0.5,Nd0.35,La0.17,Pr0.02,Sm0.02)1.2(CO3)2(OH1.04,F0.14)1.2H2O、( Ca0.73.Sr0.28,Ba0.17)1.2(Ce0.48,Nd0.15,La0.15,Pr0.04,Sm0.01)0.8(CO3)2 (OH0.75,F0.06)0.8 H2O,简化为:(Sr,Ca)2-xCex (CO3)2·(OH,F)2-x·H2O,接近理论化学式(Sr,Ca)Ce (C()2 (OH) H2O,但附加阴离子除OH外,还含有少量F-.两者均为几微米至十几微米的微小晶体,呈浸染状产出,且仅见于晚期方解石或方解石—白云石交生体中.
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