The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na...The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na2O, K2O, Rb2O, Cs2O） is up to 2.41%. The CCD system on the SMART APEX four circle single crystal diffractometer was used in this experiment to determine the structure of the sample accurately. The beryl belongs to the hexagonal system; its space group is P6/mcc. The dimensions of the unit cell are as follows： a = 0.91961（3） nm, c = 0.91969（7） nm, c/a = 1.0000, V= 0.67357 nm3, 7 = 120°, α= 90°, β = 90°. The accurate atomic coordinates of alkali metal ions and other crystallographic parameters are also obtained： Z = 2, the calculated density D = 2.754 g/cm^3 and final R （ I 〉 2 σ （/3）= 0.046 for 5597 reflections. The crystal structure was described by coordination polyhedron. Based on the data gained, a three-dimensional graph of the crystal structure of tabular beryl was made with the ATOMS 6.0 software. The refinement of crystal structure indicates that there are two main reasons for the cause of the tabular configuration： （1） The substitution of Be by Li into the tetrahedral framework weakened the stacked six-sided rings [Si6O18]^12- of the tetrahedral Si; （2） Alkalis （mainly Na and Cs） are too large to substitute in four-fold or six-fold coordination within the structure and are accommodated in the vacant channel. The accommodation of these alkalis strengthened the structure of six-sided rings of the tetrahedral Si. And other alkali metal ions and free volatile molecules such as H2O and CO2 occupy variable positions in the channel. The equation of the electrovalence is Li＋＋Na＋→Be^2＋. According to structural and compositional differences, the monoclinic crystal of tabular beryl is considered to be a new member of the beryl group. Chemical constraints of the environment, namely, the bulk-rock chemistry and the fluid-phase composition and physical-chemical conditions during the growth of the mineral may account for these occurrences of rare elements. In addition, that Li and Be have appro^mate physical parameters is also the key factor for the substitution. The direction of the mineralized hydrothermal liquid and the special occurrence conditions of the beryl such as the pH, temperature and pressure are also considered to be the main causes of the configuration of the tabular beryl.展开更多
Yarlongite occurs in ophiolitic chromitite at the Luobusha mine （29°5′N 92°5′E, about 200 km ESE of Lhasa）, Qusum County, Shannan Prefecture, Tibet Autonomous Region, People＇s Republic of China. Associa...Yarlongite occurs in ophiolitic chromitite at the Luobusha mine （29°5′N 92°5′E, about 200 km ESE of Lhasa）, Qusum County, Shannan Prefecture, Tibet Autonomous Region, People＇s Republic of China. Associated minerals are： diamond, moissanite, wiistite, iridium （＂osmiridium＂）, osmium （＂iridosmine＂）, periclase, chromite, native iron, native nickel, native chromium, forsterite, Cr-rich diopside, intermetallic compounds Ni-Fe-Cr, Ni-Cr, Cr-C, etc. Yarlongite and its associated minerals were handpicked from a large heavy mineral sample of chromitite. The metallic carbides associated with yarlongite are cohenite, tongbaite, khamrabaevite and qusongite （IMA2007-034）. Yarlongite occurs as irregular grains, with a size between 0.02 and 0.06 mm, steel-grey colour, H Mohs： 5^1/2-6. Tenacity： brittle. Cleavage： （0 0 1） perfect. Fracture： conchoidal. Chemical formula： （Cr4Fe4Ni）29C4, or （Cr,Fe,Ni）29C4, Crystal system： Hexagonal, Space Group： P63/mc, a = 18.839（2） A, c = 4.4960 （9） A, V = 745.7（2） A^3, Z = 6, Density （calc.） = 7.19 g/cm3 （with simplified formula）. Yariongite has been approved as a new mineral by the CNMNC （IMA2007-035）. Holotype material is deposited at the Geological Museum of China （No. Ml1650）.展开更多
A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet, China. Recovered minerals include diamond, coesite, moissanite, wustite, Fe-silides and a new m...A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet, China. Recovered minerals include diamond, coesite, moissanite, wustite, Fe-silides and a new mineral, luobusaite. All of these minerals were hand-picked from heavymineral separates of the podiform chromitite in the mantle peridotite of an ophiolite. The grains of luobusaite are as host mineral with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase. Luobusaite occurs as irregular grains, with 0.1-0.2 mm in size, consisting of very finegrained aggregates. The mineral is steel-grey in color, metallic luster, and opaque. The empirical formula （based on 2 for Si） is Fe0.83Si2, according to the chemical compositions of luobusaite. X-ray powder-diffraction data： orthorhombic system, space group Cmca, a = 9.874 （14） A, b = 7.784 （5） A, c= 7.829（7） A, Z=16.展开更多
We describe the new mineral species titanium, ideally Ti, found in the podiform chromitites of the Luobusha ophiolite in Tibet, People＇s Republic of China. The irregular crystals range from 0.1 to 0.6 mm in diameter ...We describe the new mineral species titanium, ideally Ti, found in the podiform chromitites of the Luobusha ophiolite in Tibet, People＇s Republic of China. The irregular crystals range from 0.1 to 0.6 mm in diameter and form an intergrowth with coesite and kyanite. Titanium is silver grey in colour, the luster is metallic, it is opaque, the streak is grayish black, and it is non-fluorescent. The mineral is malleable, has a rough to hackly fracture and has no apparent cleavage. The estimated Mohs hardness is 4, and the calculated density is 4.503 g/cm3. The composition is Ti 99.23-100.00 wt%. The mineral is hexagonal, space group P6flmmc. Unit-cell parameters are a 2.950 （2） ~, c 4.686 （1） A,V 35.32 （5） A3, Z = 2. The five strongest powder diffraction lines [d in A （hkl） （I/I0）] are： 2.569 （010） （32）, 2.254（011） （100）, 1.730 （012） （16）, 1.478 （110） （21）, and 0.9464 （121） （8）. The species and name were approved by the CNMNC （IMA 2010-044）.展开更多
A new mineral species, named naquite（FeSi）, is found in the podiform chromitites of the Luobusha ophiolite in Qusong County, Tibet, China. The detailed composition is Fe 65.65, Si 32.57 and Al 1.78 wt%. The mineral ...A new mineral species, named naquite（FeSi）, is found in the podiform chromitites of the Luobusha ophiolite in Qusong County, Tibet, China. The detailed composition is Fe 65.65, Si 32.57 and Al 1.78 wt%. The mineral is cubic, space group P213. The irregular crystals range from 15 to 50 μm in diameter and form an intergrowth with luobusaite. Naquite is steel grey in color, opaque, with a metallic lustre and gives a grayish-black streak. The mineral is brittle, has a conchoidal fracture and no apparent cleavage. The estimated Mohs hardness is 6.5, and the calculated density is 6.128 g/cm3. Unit-cell parameters are a 4.486 （4） A, V 90.28 （6）A^3, Z=4. The five strongest powder diffraction lines [d inA（hkl） （I/I0）] are： 3.1742 （110） （40）, 2.5917（111） （43）, 2.0076 （210） （100）, 1.8307 （211） （65）, and 1.1990 （321） （36）. Originally called ＇fersilicite＇, the species and new name have now been approved by the CNMNC （IMA 2010-010）.展开更多
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This investigation was supported financially by the Ministry of Education of China （Nos. 01037 and 03178）the National Natural Science Foundation of China （Nos. 40304007 and 40172036） the Fund of State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences （Nos. GPMR0530）.
文摘The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na2O, K2O, Rb2O, Cs2O） is up to 2.41%. The CCD system on the SMART APEX four circle single crystal diffractometer was used in this experiment to determine the structure of the sample accurately. The beryl belongs to the hexagonal system; its space group is P6/mcc. The dimensions of the unit cell are as follows： a = 0.91961（3） nm, c = 0.91969（7） nm, c/a = 1.0000, V= 0.67357 nm3, 7 = 120°, α= 90°, β = 90°. The accurate atomic coordinates of alkali metal ions and other crystallographic parameters are also obtained： Z = 2, the calculated density D = 2.754 g/cm^3 and final R （ I 〉 2 σ （/3）= 0.046 for 5597 reflections. The crystal structure was described by coordination polyhedron. Based on the data gained, a three-dimensional graph of the crystal structure of tabular beryl was made with the ATOMS 6.0 software. The refinement of crystal structure indicates that there are two main reasons for the cause of the tabular configuration： （1） The substitution of Be by Li into the tetrahedral framework weakened the stacked six-sided rings [Si6O18]^12- of the tetrahedral Si; （2） Alkalis （mainly Na and Cs） are too large to substitute in four-fold or six-fold coordination within the structure and are accommodated in the vacant channel. The accommodation of these alkalis strengthened the structure of six-sided rings of the tetrahedral Si. And other alkali metal ions and free volatile molecules such as H2O and CO2 occupy variable positions in the channel. The equation of the electrovalence is Li＋＋Na＋→Be^2＋. According to structural and compositional differences, the monoclinic crystal of tabular beryl is considered to be a new member of the beryl group. Chemical constraints of the environment, namely, the bulk-rock chemistry and the fluid-phase composition and physical-chemical conditions during the growth of the mineral may account for these occurrences of rare elements. In addition, that Li and Be have appro^mate physical parameters is also the key factor for the substitution. The direction of the mineralized hydrothermal liquid and the special occurrence conditions of the beryl such as the pH, temperature and pressure are also considered to be the main causes of the configuration of the tabular beryl.
基金supported by the National Natural Science Foundation of China(Grant 40472025,40672030 and 40872043).
文摘Yarlongite occurs in ophiolitic chromitite at the Luobusha mine （29°5′N 92°5′E, about 200 km ESE of Lhasa）, Qusum County, Shannan Prefecture, Tibet Autonomous Region, People＇s Republic of China. Associated minerals are： diamond, moissanite, wiistite, iridium （＂osmiridium＂）, osmium （＂iridosmine＂）, periclase, chromite, native iron, native nickel, native chromium, forsterite, Cr-rich diopside, intermetallic compounds Ni-Fe-Cr, Ni-Cr, Cr-C, etc. Yarlongite and its associated minerals were handpicked from a large heavy mineral sample of chromitite. The metallic carbides associated with yarlongite are cohenite, tongbaite, khamrabaevite and qusongite （IMA2007-034）. Yarlongite occurs as irregular grains, with a size between 0.02 and 0.06 mm, steel-grey colour, H Mohs： 5^1/2-6. Tenacity： brittle. Cleavage： （0 0 1） perfect. Fracture： conchoidal. Chemical formula： （Cr4Fe4Ni）29C4, or （Cr,Fe,Ni）29C4, Crystal system： Hexagonal, Space Group： P63/mc, a = 18.839（2） A, c = 4.4960 （9） A, V = 745.7（2） A^3, Z = 6, Density （calc.） = 7.19 g/cm3 （with simplified formula）. Yariongite has been approved as a new mineral by the CNMNC （IMA2007-035）. Holotype material is deposited at the Geological Museum of China （No. Ml1650）.
基金This work was financially supported by the National Natural Science Foundation of China(Grant 40620120098 and 40472025).
文摘A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet, China. Recovered minerals include diamond, coesite, moissanite, wustite, Fe-silides and a new mineral, luobusaite. All of these minerals were hand-picked from heavymineral separates of the podiform chromitite in the mantle peridotite of an ophiolite. The grains of luobusaite are as host mineral with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase. Luobusaite occurs as irregular grains, with 0.1-0.2 mm in size, consisting of very finegrained aggregates. The mineral is steel-grey in color, metallic luster, and opaque. The empirical formula （based on 2 for Si） is Fe0.83Si2, according to the chemical compositions of luobusaite. X-ray powder-diffraction data： orthorhombic system, space group Cmca, a = 9.874 （14） A, b = 7.784 （5） A, c= 7.829（7） A, Z=16.
基金supported by the National Natural Science Foundation of China (40472025, 40620120098,40872043)
文摘We describe the new mineral species titanium, ideally Ti, found in the podiform chromitites of the Luobusha ophiolite in Tibet, People＇s Republic of China. The irregular crystals range from 0.1 to 0.6 mm in diameter and form an intergrowth with coesite and kyanite. Titanium is silver grey in colour, the luster is metallic, it is opaque, the streak is grayish black, and it is non-fluorescent. The mineral is malleable, has a rough to hackly fracture and has no apparent cleavage. The estimated Mohs hardness is 4, and the calculated density is 4.503 g/cm3. The composition is Ti 99.23-100.00 wt%. The mineral is hexagonal, space group P6flmmc. Unit-cell parameters are a 2.950 （2） ~, c 4.686 （1） A,V 35.32 （5） A3, Z = 2. The five strongest powder diffraction lines [d in A （hkl） （I/I0）] are： 2.569 （010） （32）, 2.254（011） （100）, 1.730 （012） （16）, 1.478 （110） （21）, and 0.9464 （121） （8）. The species and name were approved by the CNMNC （IMA 2010-044）.
基金supported financially by the National Natural Science Foundation of China (Grant No. 40472025, 40620120098,40872043)
文摘A new mineral species, named naquite（FeSi）, is found in the podiform chromitites of the Luobusha ophiolite in Qusong County, Tibet, China. The detailed composition is Fe 65.65, Si 32.57 and Al 1.78 wt%. The mineral is cubic, space group P213. The irregular crystals range from 15 to 50 μm in diameter and form an intergrowth with luobusaite. Naquite is steel grey in color, opaque, with a metallic lustre and gives a grayish-black streak. The mineral is brittle, has a conchoidal fracture and no apparent cleavage. The estimated Mohs hardness is 6.5, and the calculated density is 6.128 g/cm3. Unit-cell parameters are a 4.486 （4） A, V 90.28 （6）A^3, Z=4. The five strongest powder diffraction lines [d inA（hkl） （I/I0）] are： 3.1742 （110） （40）, 2.5917（111） （43）, 2.0076 （210） （100）, 1.8307 （211） （65）, and 1.1990 （321） （36）. Originally called ＇fersilicite＇, the species and new name have now been approved by the CNMNC （IMA 2010-010）.
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.
