Crystal structure of the OH-dominant gadolinite-(Y) analogue (Y,Ca)2(Fe,□)Be2Si2O8(OH,O)2 from Heftetjern pegmatite, Norway.

A hydroxyl-dominant analogue of gadolinite-(Y) (OH-Gad) has been discovered in the Heftetjern granitic pegmatite, southern Norway, in association with late-stage rare-earth-element containing minerals. The empirical formula, based on ten O atoms per formula unit, is (Y1.285Ca0.55Ce0.07La0.04Nd0.01)Σ1.955(Fe2+0.57□0.43)Be2.02Si1.995O8.48(OH)1.52. The mineral is monoclinic, space group P21/c, a = 4.7514 (10), b = 7.5719 (16), c = 9.9414 (2) Å, β = 90.015 (4)°, V = 357.663 (3) Å3 and Z = 2. The density calculated using the empirical formula is 3.903 g cm-3. The crystal structure was refined to R = 0.0217 for 776 reflections with I > 2σ(I). OH-Gad is isostructural with gadolinite-(Y) and it is characterized by the predominance of OH- over O2- at the anionic Ø-site. The refined crystal-chemical formula is: A(Y1.25Ca0.55Ce0.2)X(Fe2+0.57□0.43)ZBe2TSi2O8Ø[(OH)0.86O0.59(OH)*0.55] (Z = 2). The possible orientation and local environment of the hydroxyl group were suggested based on bond-valence sum calculations and geometrical analysis of the crystal structure. The infrared spectrum confirms disordering of H atoms. OH-Gad seems to be a potentially new mineral, the first simultaneously hydroxyl- and iron-dominant member of the gadolinite subgroup. It is an OH-analogue of gadolinite-(Y) and an Fe2+-analogue of hingganite-(Y).

[1]  N. Chukanov,et al.  The crystal chemistry of lamprophyllite-related minerals: a review , 2016 .

[2]  M. Brik,et al.  Luminescence of Ce3+-Doped MB2Si2O8 (M = Sr, Ba): A Deeper Insight into the Effects of Electronic Structure and Stokes Shift , 2016 .

[3]  D. Malczewski,et al.  222Rn and 220Rn emanations as a function of the absorbed α-doses from select metamict minerals , 2015 .

[4]  I. Nakai,et al.  Mn-BEARING HELLANDITE-(Y) FROM THE HEFTETJERN PEGMATITE, TØRDAL, NORWAY , 2015 .

[5]  E. Selivanova,et al.  Minerals of the gadolinite-(Y)-hingganite-(Y) series in the alkali granite pegmatites of the Kola Peninsula , 2014, Geology of Ore Deposits.

[6]  F. Hawthorne,et al.  Agakhanovite-(Y), ideally (YCa)⃞2KBe3Si12O30, a new milarite-group mineral from the Heftetjern pegmatite, Tørdal, Southern Norway: Description and crystal structure , 2014 .

[7]  P. Uher,et al.  THE CRYSTAL CHEMISTRY OF GADOLINITE-DATOLITE GROUP SILICATES , 2014 .

[8]  V. Ratkin,et al.  Dal’negosrk skarn deposit, Sikhote-Alin: Stages and sources of matter for borosilicate ores , 2014, Doklady Earth Sciences.

[9]  N. Chukanov.  Infrared spectra of mineral species: Extended library , 2013 .

[10]  W. White,et al.  Hydrothermal synthesis of Eu2+-activated borosilicate phosphors with the danburite structure , 2012 .

[11]  K. S. Mann,et al.  Verification of some low-Z silicates as gamma-ray shielding materials , 2012 .

[12]  R. Angel,et al.  Crystal chemistry and low-temperature behavior of datolite: A single-crystal X-ray diffraction study , 2010 .

[13]  E. Tillmanns,et al.  Heftetjernite, a new scandium mineral from the Heftetjern pegmatite, Tørdal, Norway , 2010 .

[14]  F. Hawthorne,et al.  Triclinic titanite from the Heftetjern granitic pegmatite, Tørdal, southern Norway , 2009, Mineralogical Magazine.

[15]  Yuhua Wang,et al.  Electronic properties and rare-earth ions photoluminescence behaviors in borosilicate: SrB2Si2O8 , 2009 .

[16]  Sea-Fue Wang,et al.  Densification and microwave dielectric properties of CaO–B2O3–SiO2 system glass–ceramics , 2008 .

[17]  S. Morales-Ruano,et al.  Investigation of datolite (CaB[SiO4/(OH)]) from basalts in the Northern Apennines ophiolites (Italy): Genetic implications , 2008 .

[18]  G. Sheldrick.  A short history of SHELX. , 2008, Acta crystallographica. Section A, Foundations of crystallography.

[19]  Jusheng Ma,et al.  Dielectric Properties of LTCC System of Al2O3 and Borosilicate Glass , 2007 .

[20]  S. Merlino,et al.  Fluorcalciobritholite, Ca,REE)5[(Si,P)O4]3F, a new mineral: description and crystal chemistry , 2007 .

[21]  F. Bellatreccia,et al.  Datolite: a new occurrence in volcanic ejecta (Pitigliano, Toscana, Italy) and crystal-structure refinement , 2006 .

[22]  William E. Lee,et al.  An Introduction to Nuclear Waste Immobilisation , 2005 .

[23]  L. Ottolini,et al.  Replacement textures involving four scandium silicate minerals in the Heftetjern granitic pegmatite, Norway , 2004 .

[24]  D. Schubert.  Borates in Industrial Use , 2003 .

[25]  J. Jean,et al.  Sintering of a Crystallizable K_2O–CaO–SrO–BaO–B_2O_3–SiO_2 Glass with Titania Present , 2002 .

[26]  G. Ivaldi,et al.  Kristiansenite, a new calcium–scandium–tin sorosilicate from granite pegmatite in Tørdal, Telemark, Norway , 2002 .

[27]  Roberta Oberti,et al.  Re-definition, nomenclature and crystal-chemistry of the hellandite group , 2002 .

[28]  V. Rybakov,et al.  Preparation, Structure, and Properties of New Laser Crystals Y2SiBe2O7and Y2Al(BeB)O7 , 2002 .

[29]  F. Demartin,et al.  CHARACTERIZATION OF GADOLINITE-GROUP MINERALS USING CRYSTALLOGRAPHIC DATA ONLY: THE CASE OF HINGGANITE-(Y) FROM CUASSO AL MONTE, ITALY , 2001 .

[30]  N. Chukanov,et al.  A new data on calcybeborosilite-(Y), (REE,Ca)2(B,Be)2[SiO4]2(OH,O)2 , 2000 .

[31]  F. Pezzotta,et al.  Chemical and paragenetic data on gadolinite-group minerals from Baveno and Cuasso al Monte, southern Alps, Italy , 1999 .

[32]  E. Belokoneva,et al.  ELECTRON DENSITY AND CHEMICAL BONDING IN NATURAL BOROSILICATE DATOLITE FROM PRECISION X-RAY DIFFRACTION DATA , 1998 .

[33]  I. Pekov,et al.  CRYSTAL STRUCTURE OF "CALCYBEBOROSILITE" AND ITS PLACE IN THE DATOLITE-GADOLINITE ISOMORPHOUS SERIES , 1996 .

[34]  A. Merzhanov,et al.  SHS extrusion of electrode materials and their application for electric-spark alloying of steel surfaces , 1992 .

[35]  Rao Tummala,et al.  Ceramic and Glass‐Ceramic Packaging in the 1990s , 1991 .

[36]  E. V. Kuznetsov,et al.  Boron building ceramic protecting against neutron radiation , 1990 .

[37]  L. S. Opaleichuk,et al.  New types of filters , 1989 .

[38]  S. Bergstøl,et al.  Scandian ixiolite, pyrochlore and bazzite in granite pegmatite in terdal, Telemark, Norway. A contribution to the mineralogy and geochemistry of scandium and tin , 1988 .

[39]  N. P. Guseva,et al.  Using datolite and diopside raw materials in the electrical engineering industry , 1988 .

[40]  W. Simmons,et al.  Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil , 1986 .

[41]  I. D. Brown,et al.  Bond‐valence parameters obtained from a systematic analysis of the Inorganic Crystal Structure Database , 1985 .

[42]  I. Nakai,et al.  A refinement of the crystal structure of gadolinite , 1984 .

[43]  J. Verstegen,et al.  Luminescence of Eu2+-activated SrB2Si2O8 , 1972 .