Hydroxycalciopyrochlore,ideally （Ca,Na,U,□）2（Nb,Ti）2O6（OH）,cubic,is a new mineral species （IMA2011-026） within the pyrochlore supergroup that was found occurring at the Maoniuping mine,Mianning County,Xichang...Hydroxycalciopyrochlore,ideally （Ca,Na,U,□）2（Nb,Ti）2O6（OH）,cubic,is a new mineral species （IMA2011-026） within the pyrochlore supergroup that was found occurring at the Maoniuping mine,Mianning County,Xichang prefecture,Sichuan Province,southwest China.The mineral is found in an alkali feldspar granite rare-earth ore deposit （26-27 Ma）.Associated minerals include calcite,barite,celestine,albite,aegirine,aegirine-augite,fluorite,parasite-（Ce）,thorite,thorianite,zircon,galena,sphalerite,magnetite,and pyrite.Crystals occur mostly as octahedra,and less often as dodecahedra and tetrahexahedra or combinations thereof.Some occur with an allotriomorphic habit with a thick triangular tabular form.Crystals generally range from 0.1 to 1 mm in size.The mineral is brownishblack,greenish-black and black on fresh sections with a brown streak.The crystal is translucent,and has a greasy lustre on fresh sections.It is metamict without any observed parting or cleavage and with a conchoidal fracture.The Vickers microhardness is 572 kg/mm2 （5-6 on the Mohs hardness scale）.The density measured by hydrostatic weighing is 5.10（3） g/cm3.The strongest four reflections in the X-ray powder-diffraction pattern [d in（A） （Ⅰ） hkl] are：2.9657 （100） 2 2 2,1.8142 （34） 0 4 4,1.5463 （21） 2 2 6,2.5688 （18） 0 0 4.The unit-cell parameters are a =10.381（4） （A）,V=1118.7（7）（A）3,Z =8.The structure was solved and refined in the space group Fd3m with R =0.09.The empirical formula is （Ca0.74Na0.5sU0.40Ce0.05Fe0.02□0.21）2.00（Nb1.15Ti0.s0Ta0.03Al0.01Mg0.01）2.00O6.02 [（OH）1.01F0.09]1.10,on the basis of 2 atoms of B pfu; the simplified formula is （Ca,Na,U,□）2（Nb,Ti）2O6（OH）.Type material is deposited in the Geological Museum of China,Beijing,People＇s Republic of China,catalogue number M11800.展开更多
基金supported by the National Natural Science Foundation of China (grant #41172052)
文摘Hydroxycalciopyrochlore,ideally （Ca,Na,U,□）2（Nb,Ti）2O6（OH）,cubic,is a new mineral species （IMA2011-026） within the pyrochlore supergroup that was found occurring at the Maoniuping mine,Mianning County,Xichang prefecture,Sichuan Province,southwest China.The mineral is found in an alkali feldspar granite rare-earth ore deposit （26-27 Ma）.Associated minerals include calcite,barite,celestine,albite,aegirine,aegirine-augite,fluorite,parasite-（Ce）,thorite,thorianite,zircon,galena,sphalerite,magnetite,and pyrite.Crystals occur mostly as octahedra,and less often as dodecahedra and tetrahexahedra or combinations thereof.Some occur with an allotriomorphic habit with a thick triangular tabular form.Crystals generally range from 0.1 to 1 mm in size.The mineral is brownishblack,greenish-black and black on fresh sections with a brown streak.The crystal is translucent,and has a greasy lustre on fresh sections.It is metamict without any observed parting or cleavage and with a conchoidal fracture.The Vickers microhardness is 572 kg/mm2 （5-6 on the Mohs hardness scale）.The density measured by hydrostatic weighing is 5.10（3） g/cm3.The strongest four reflections in the X-ray powder-diffraction pattern [d in（A） （Ⅰ） hkl] are：2.9657 （100） 2 2 2,1.8142 （34） 0 4 4,1.5463 （21） 2 2 6,2.5688 （18） 0 0 4.The unit-cell parameters are a =10.381（4） （A）,V=1118.7（7）（A）3,Z =8.The structure was solved and refined in the space group Fd3m with R =0.09.The empirical formula is （Ca0.74Na0.5sU0.40Ce0.05Fe0.02□0.21）2.00（Nb1.15Ti0.s0Ta0.03Al0.01Mg0.01）2.00O6.02 [（OH）1.01F0.09]1.10,on the basis of 2 atoms of B pfu; the simplified formula is （Ca,Na,U,□）2（Nb,Ti）2O6（OH）.Type material is deposited in the Geological Museum of China,Beijing,People＇s Republic of China,catalogue number M11800.
