From structure topology to chemical composition.VIII. Titanium silicates: the crystal chemistry of mosandrite from type locality of Låven (Skådön), Langesundsfjorden, Larvik, Vestfold, Norway

2008 ◽  
Vol 72 (4) ◽  
pp. 887-897 ◽  
Author(s):  
E. Sokolova ◽  
F. Cámara
Keyword(s):  
Crystal Structure ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Type Locality ◽  
Titanium Silicate ◽  
Structure Topology ◽  
Titanium Silicates ◽  
And Topology ◽  
Group I

AbstractThe crystal structure of mosandrite, ideally Na2Ca4REETi(Si2O7)2OF3, a = 7.4184(8), b = 5.6789(6), c = 18.873(2) Å, β = 101.410(2)°, V = 779.35(5) Å3, space group P21/c, Z = 2, Dcalc = 3.363 g.cm-3, from the type locality, Låven (Skådön), Langesundsfjorden, Larvik, Vestfold, Norway, has been refined to Ri = 6.33% on the basis of 1113 unique reflections F°≥4σF. Electron microprobe analysis gave the empirical formula Na1.99(Ca3.93Sr0.02)Σ3.95(Ce0.41La0.16Nd0.13Pr0.04Sm0.02Dy0.01Y0.13)Σ0.90 (Ti0.864+Nb0.08Zr0.05)Σ0.99(Si207)2(F1.20O0.80)Σ2.00F2, Z = 2, calculated on the basis of 18 (O + F) a.p.f.u.. The crystal structure of mosandrite is a framework of TS (titanium silicate) blocks. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). The TS block in mosandrite exhibits linkage and stereochemistry typical for Group I (Ti = 1 a.p.f.u.) Ti-disilicate minerals: two H sheets connect to the O sheet such that two (Si2O7) groups link to the trans edges of a Na polyhedron of the O sheet. The O sheet cations give Na(NaCa)Ti (4 a.p.f.u.). The TS blocks link via common vertices of (Si2O7) groups and common vertices and edges of Ca-dominant MH and Ap polyhedra. Two adjacent TS blocks are related by the glide plane cy. Composition and topology of the TS block in mosandrite and rinkite are identical. The crystal structure of mosandrite from the type locality is topologically and chemically identical to that of rinkite from the type locality of Kangerdluarssuk, Greenland.

scholarly journals From structure topology to chemical composition. VI. Titanium silicates: the crystal structure and crystal chemistry of bornemanite, a group III Ti-disilicate mineral

2007 ◽  
Vol 71 (06) ◽  
pp. 593-610 ◽  
Author(s):  
F. Cámara ◽  
E. Sokolova
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Titanium Silicate ◽  
Group Iii ◽  
Structure Topology ◽  
Titanium Silicates ◽  
Alkaline Massif

Abstract The crystal structure of bornemanite, ideally Na6☐BaTi2Nb(Si2O7)2(PO4)O2(OH)F, a = 5.4587(3), b = 7.1421(5), c = 24.528(2) Å, α = 96.790(1), β = 96.927(1), γ = 90.326(1)°, V = 942.4(2) Å3, space group (P1̄), Z = 2, Dcalc. = 3.342 g cm–3, from the Lovozero alkaline massif, Kola Peninsula, Russia, has been solved and refined to R1 = 6.36% on the basis of 4414 unique reflections (Fo >4sF). Electron microprobe analysis yielded the empirical formula (Na6.07Mn2+ 0.23Ca0.06☐0.64)Σ 7.00 (Ba0.73K0.13Sr0.06☐0.08)Σ 1.00(Ti2.05Nb0.80Zr0.02Ta5+ 0.01Fe3+ 0.03Al0.02Mn2+ 0.06Mg0.01)Σ 3.00(Si2O7)2(P0.97O4)O2 [F1.27(OH)0.74]Σ 2.01. The crystal structure of bornemanite is a combination of a TS (titanium silicate) block and an I (intermediate) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). The TS block exhibits linkage and stereochemistry typical for Group III (Ti = 3 a.p.f.u.) of Ti-disilicate minerals: two H sheets connect to the O sheet such that two (Si2O7) groups link to the trans edges of a Ti octahedron of the O sheet. The O sheet cations give Na3Ti (4 a.p.f.u.). The TS block has two different H sheets, H1 and H2, where (Si2O7) groups link to [5]Ti and [6]Nb polyhedra, and there are two peripheral sites which are occupied by Ba and Na, respectively. There are two I blocks: the I1 block is a layer of Ba atoms; the I2 block consists of Na polyhedra and (PO4) tetrahedra.

From structure topology to chemical composition. XI. Titanium silicates: crystal structures of innelite-1T and innelite-2M from the Inagli massif, Yakutia, Russia, and the crystal chemistry of innelite

2011 ◽  
Vol 75 (4) ◽  
pp. 2495-2518 ◽  
Author(s):  
E. Sokolova ◽  
F. Cámara ◽  
F. C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Titanium Silicate ◽  
Space Group ◽  
Group Iii ◽  
Structure Topology ◽  
Titanium Silicates

AbstractThe crystal structures of two polytypes of innelite, ideally Ba4Ti2Na2M2+Ti(Si2O7)2[(SO4) (PO4)]O2[O(OH)] where M2+ = Mn, Fe2+, Mg, Ca: innelite-1T, a 5.4234(9), b 7.131(1), c 14.785(3) Å, α 98.442(4), β 94.579(3), γ 90.009(4)°, V 563.7(3) Å3, space group P1̄, Dcalc = 4.028 g/cm3, Z = 1; and innelite-2M, a 5.4206(8), b 7.125(1), c 29.314(4) Å, 0 94.698(3)°, V 1128.3(2) Å3, space group P2/c, Dcalc.= 4.024 g/cm3, Z = 2, from the Inagli massif, Yakutia, Russia, have been refined to R values of 8.99 and 7.60%, respectively. Electron-microprobe analysis gave the empirical formula for innelite as (Ba3.94Sr0.06)Σ4.00(Na2.16Mn0.382+Fe2+0.17Mg0.15Ca0.10☐0.04)Σ3(Ti2.97Nb0.02Al0.02)Σ3.01Si4.01 (S1.02P0.81☐0.17)Σ2H1.84O25.79F0.21 which is equivalent to (Ba3.94Sr0.06)Σ4.00(Ti1.97Nb0.02Al0.02)Σ2.01 [(OH0.99F0.21)Σ1.20O0.80], calculated on the basis of 26 (O + F) anions, with H2O calculated from structure refinement. The crystal structure of innelite is a combination of a TS (titanium silicate) block and an I (intermediate) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral) and exhibits linkage and stereochemistry typical for Ti-disilicate minerals of Group III (Ti = 3 a.p.f.u.): two H sheets connect to the O sheet such that two (Si2O7) groups link to the trans edges of a Ti octahedron of the O sheet. The I block contains T sites, statistically occupied by S and P, and Ba atoms. In the structures of innelite-1T and innelite-2M, TS blocks are related by an inversion centre and a cy glide plane, respectively. HRTEM images show a coherent intergrowth of the two polytypes, together with an as-yet unidentified ∼10 Å phase.

scholarly journals From structure topology to chemical composition. X. Titanium silicates: the crystal structure and crystal chemistry of nechelyustovite, a group III Ti-disilicate mineral

2009 ◽  
Vol 73 (5) ◽  
pp. 753-775 ◽  
Author(s):  
F. Cámaraite ◽  
E. Sokolova
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Titanium Silicate ◽  
Group Iii ◽  
Structure Topology ◽  
Titanium Silicates ◽  
Peripheral Site ◽  
Alkaline Massif

AbstractThe crystal structure of nechelyustovite, ideally Na4Ba2Mn1.5☐2.5Ti5Nb(Si2O7)4O4(OH)3F(H2O)6, a 5.447(1) Å, b 7.157(1) Å, c 47.259(9) Å, α 95.759(4)°, β 92.136(4)°, γ 89.978(4)°, V 1831.7(4) Å3, space group P, Z = 2, Dcalc. 3.041 g cm–3, from Lovozero alkaline massif, Kola Peninsula, Russia, has been solved and refined to R1 = 13.9% on the basis of 1745 unique reflections (Fo > 15σF). Electron microprobe analysis yielded the empirical formula (H20)6.01, Z = 2, calculated on the basis of 42 (O + F) a.p.f.u., H2O and OH are calculated from structure refinement (H2O = 6 p.f.u.; F + OH = 4 p.f.u.). The crystal structure of nechelyustovite is a combination of a TS (titanium silicate) block and an I (intermediate) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). The TS block exhibits linkage and stereochemistry typical for Group III (Ti = 3 a.p.f.u.) of Ti-disilicate minerals: two H sheets connect to the O sheet such that two (Si2O7) groups link to the trans edges of a Ti octahedron of the O sheet. There are two distinct TS blocks of the same topology, TS1 and TS2, that differ in the cations of the O sheet, [(Na1.5Mn1☐0.5)Ti] and [(Na2Mn0.5☐0.5)Ti] (4 a.p.f.u.) respectively. The TS1 and TS2 blocks have two different H sheets, H1,2 and H3,4, where (Si2O7) groups link to [5]- and [6]-coordinated (Ti,Nb) polyhedra respectively. There are three peripheral sites, AP(1—3), occupied mainly by Ba (less Sr and K) at 96, 86 and 26% and one peripheral site AP(4) occupied by Na at 50%. There are two I blocks: the I1 block is a layer of Ba atoms; the I2 block consists of H2O groups and AP(3) atoms. TS blocks alternate with I blocks or link through hydrogen bonds (as in epistolite). There is a sequence of four TS blocks and three I blocks per the c cell parameter: TS2 — I1 — TS1 — I2 — TS1 — I1 — TS2.

From structure topology to chemical composition. XXIV. Revision of the crystal structure and chemical formula of vigrishinite, NaZnTi4(Si2O7)2O3(OH)(H2O)4, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia

2018 ◽  
Vol 82 (4) ◽  
pp. 787-807 ◽  
Author(s):  
Elena Sokolova ◽  
Frank C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Structural Formula ◽  
Titanium Silicate ◽  
Structure Topology ◽  
Alkaline Massif ◽  
The Ideal

ABSTRACTThe crystal structure of vigrishinite, ideally NaZnTi4(Si2O7)2O3(OH)(H2O)4, a murmanite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia, was refined in space group C$\bar 1$, a = 10.530(2), b = 13.833(3), c = 11.659(2) Å, α = 94.34(3), β = 98.30(3), γ = 89.80(3)°, V = 1675.5(2.1) Å3 and R1 = 12.52%. Based on electron-microprobe analysis, the empirical formula calculated on 22 (O + F), with two constraints derived from structure refinement, OH + F = 1.96 pfu and H2O = 3.44 pfu, is: (Na0.67Zn0.21Ca0.05□1.07)Σ2 (Zn0.86□1.14)Σ2(Zn0.14□0.36)Σ0.5(Ti2.60Nb0.62Mn0.30${\rm Fe}_{{\rm 0}{\rm. 23}}^{{\rm 2 +}} $Mg0.10Zr0.06Zn0.05Al0.03Ta0.01)Σ4(Si4.02O14) [O2.60(OH)1.21F0.19]Σ4[(H2O)3.44(OH)0.56]Σ4{Zn0.24P0.03K0.03Ba0.02} with Z = 4. It seems unlikely that constituents in the {} belong to vigrishinite itself. The crystal structure of vigrishinite is an array of TS blocks (Titanium Silicate) connected via hydrogen bonds. The TS block consists of HOH sheets (H = heteropolyhedral and O = octahedral) parallel to (001). In the O sheet, the Ti-dominant MO(1,2) sites, Na-dominant MO(3) and □-dominant MO(4) sites give ideally Na□Ti2 pfu. In the H sheet, the Ti-dominant MH(1,2) sites, Zn-dominant AP(1) and vacant AP(2) sites give ideally Zn□Ti2 pfu. The MH and AP(1) polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula of vigrishinite of the form ${\rm A}_{\rm 2}^{P} {\rm M}_{\rm 2}^{\rm H} {\rm M}_{\rm 4}^{\rm O} $(Si2O7)2(${\rm X}_{\rm M}^{\rm O} $)2(${\rm X}_{\rm A}^{\rm O} $)2(${\rm X}_{{\rm M,A}}^{P} $)4 is Zn□Ti2Na□Ti2(Si2O7)2O2O(OH)(H2O)4. Vigrishinite is a Zn-bearing, Na-poor and OH-rich analogue of murmanite, ideally Na2Ti2Na2Ti2(Si2O7)2O2O2(H2O)4. Murmanite and vigrishinite are related by the following substitution: H(${\rm Na}_{\rm 2}^{\rm +} $)mur + O(Na+)mur + O(O2–)mur ↔ H(Zn2+)vig + H(□)vig + O(□)vig + O[(OH)–]vig. The doubling of the t1 and t2 translations of vigrishinite compared to those of murmanite is due to the order of Zn and □ in the H sheet and Na and □ in the O sheet of vigrishinite.

From structure topology to chemical composition. XII. Titanium silicates: the crystal chemistry of rinkite, Na2Ca4REETi(Si2O7)2OF3

2011 ◽  
Vol 75 (6) ◽  
pp. 2755-2774 ◽  
Author(s):  
F. Cámara ◽  
E. Sokolova ◽  
F. C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Data Transmission ◽  
Intensity Data ◽  
Titanium Silicate ◽  
X Ray ◽  
Structure Topology ◽  
Titanium Silicates ◽  
Group I ◽  
Transmission Electron

AbstractRinkite, ideally Na2Ca4REETi(Si2O7)2OF3, is a common mineral in alkaline and peralkaline rocks. The crystal structures of five rinkite crystals from three alkaline massifs: Ilimaussaq, Greenland; Khibiny, Kola Peninsula, Russia and Mont Saint-Hilaire, Canada, have been refined as two components related by the TWIN matrix (–1 0 0, 0 –1 0, 1 0 1) (Mo-αa radiation). The crystals, a = 7.4132-7.4414, b = 5.6595-5.6816, c = 18.8181-18.9431 Å, β = 101.353-101.424(2)°, V= 776.1-786.7 Å3, space group P21lc, Z = 2, Dcalc = 3.376—3.502 g cm–3, were analysed using an electron microprobe subsequent to collection of the X-ray intensity data. Transmission electron microscopy confirmed the presence of pseudomerohedral twinning in rinkite crystals. The crystal structure of rinkite is a framework of TS (titanium silicate) blocks. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). The TS block in rinkite exhibits linkage and stereochemistry typical for Group I (Ti = 1 a.p.f.u.) of Ti disilicate minerals: two H sheets connect to the O sheet such that two (Si2O7) groups link to the trans edges of a Na polyhedron of the O sheet. The crystal chemistry of rinkite and nacareniobsite-(Ce) is discussed.

The crystal structure of voggite, a new hydrated Na–Zr hydroxide–phosphate–carbonate mineral

1990 ◽  
Vol 54 (376) ◽  
pp. 495-500 ◽  
Author(s):  
Jan T. Szymański ◽  
Andrew C. Roberts
Keyword(s):  
Crystal Structure ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Bidentate Ligand ◽  
New Mineral ◽  
Chemical Formula ◽  
The Third ◽  
Carbonate Ion ◽  
Phosphate Carbonate

AbstractThe crystal structure of the new mineral voggite, Na2Zr(PO4)(CO3)(OH).2H2O , from the Francon quarry, Montreal, Quebec, Canada, has been solved in order to determine the correct chemical formula, as conventional electron microprobe methods were found unreliable. The unit cell is monoclinic, I2/m, with a = 12.261(2), b = 6.561(1), c = 11.757(2)Å, β = 116.19(2)°. The structure consists of layers of edge-sharing Zr-O pentagonal bipyramids, separated by layers of Na-(O,H2O) octahedra. The carbonate ion acts as a bidentate ligand in the Zr-O polyhedron, the third oxygen atom being bonded to the Na atom. The phosphate group is bonded to three different Zr atoms and to a Na atom. The Zr-O bond lengths vary from 2.067 to 2.283 (mean 2.140Å), while Na-O are between 2.304 and 2.773, (σ = 0.006Å, mean 2.480Å). The carbonate and phosphate bonds are normal. It is inferred from the structure that the columns of octahedrally coordinated Na atoms can easily be broken apart when subjected to the heat generated by the electron microprobe beam, with the subsequent expulsion of water. This gives rise to ‘mobile’ Na atoms, which make quantitative electron microprobe analysis extremely difficult. The structure allows the ‘liberated’ Na atoms to move freely within planes parallel to .

scholarly journals From structure topology to chemical composition. XXIII. Revision of the crystal structure and chemical formula of zvyaginite, Na2ZnTiNb2(Si2O7)2O2(OH)2(H2O)4, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia

2017 ◽  
Vol 81 (6) ◽  
pp. 1533-1550 ◽  
Author(s):  
E. Sokolova ◽  
A. Genovese ◽  
A. Falqui ◽  
F.C. Hawthorne ◽  
F. Cámara
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
Microprobe Analysis ◽  
Structural Formula ◽  
Chemical Formula ◽  
Titanium Silicate ◽  
Structure Topology ◽  
Diffraction Patterns ◽  
Alkaline Massif ◽  
The Ideal

AbstractThe crystal structure and chemical formula of zvyaginite, ideally Na2ZnTiNb2(Si2O7)2O2(OH)2(H2O)4, a lamprophyllite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia have been revised. The crystal structurewas refined with a new origin in space group C1, a = 10.769(2), b = 14.276(3), c = 12.101(2) Å, α = 105.45(3), β = 95.17(3), γ = 90.04(3)°, V = 1785.3(3.2) Å3, R1 = 9.23%. The electron-microprobe analysis gave the following empirical formula [calculated on 22 (O + F)]: (Na0.75Ca0.09K0.04□1.12)Σ2 (Na1.12Zn0.88Mn0.17Fe2+0.04□0.79)Σ3 (Nb1.68Ti1.25Al0.07)Σ3 (Si4.03O14)O2 [(OH)1.11F0.89]Σ2(H2O)4, Z = 4. Electron-diffraction patterns have prominent streaking along c* and HRTEM images show an intergrowth of crystalline zvyaginite with two distinct phases, both of which are partially amorphous. The crystal structure of zvyaginite is an array of TS (Titanium-Silicate) blocks connected via hydrogen bonds between H2O groups. The TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the [6]MO(1,4,5) sites are occupied mainly by Ti, Zn and Na and the [6]MO(2,3) sites are occupied by Na at less than 50%. In the H sheet, the [6]MH(1,2) sites are occupied mainly by Nb and the [8]AP(1) and [8]AP(2) sites are occupied mainly by Na and □. The MH and AP polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula is Na□Nb2NaZn□Ti(Si2O7)2O2(OH)2(H2O)4. Zvyaginite is a Zn-bearing and Na-poor analogue of epistolite, ideally (Na□)Nb2Na3Ti(Si2O7)2O2(OH)2(H2O)4. Epistolite and zvyaginite are related by the following substitution in the O sheet of the TS-block: (Naþ 2 )epi↔Zn2+ zvy +□zvy. The doubling of the t1 and t2 translations of zvyaginite relative to those of epistolite is due to the order of Zn and Na along a (t1) and b (t2) in the O sheet of zvyaginite.

From structure topology to chemical composition. XIV. Titanium silicates: refinement of the crystal structure and revision of the chemical formula of mosandrite, (Ca3REE)[(H2O)2Ca0.5□0.5]Ti(Si2O7)2(OH)2(H2O)2, a Group-I mineral from the Saga mine, Morje, Porsgrunn, Norway

2013 ◽  
Vol 77 (6) ◽  
pp. 2753-2771 ◽  
Author(s):  
E. Sokolova ◽  
F. C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Long Range ◽  
Structure Refinement ◽  
Alkali Cations ◽  
Oh Groups ◽  
Structure Topology ◽  
Titanium Silicates ◽  
Group I ◽  
Ideal Composition ◽  
Cation Sites

AbstractThe crystal structure of mosandrite, ideally (Ca3REE)[(H2O)2Ca0.5☐0.5]Ti(Si2O7)2(OH)2(H2O)2, from the Saga mine, Morje, Porsgrunn, Norway, has been refined as two components related by the TWIN matrix ( 0 0, 0 0, 1 0 1): a 7.4222(3), b 5.6178(2), c 18.7232(7) Å, β 101.4226(6)°, V = 765.23(9) Å3, space group P21/c, Dcalc. = 3.361 g.cm–3, R1 = 3.69% using 1347 observed (Fo > 4σF) reflections. The empirical formula of mosandrite (EMPA) was calculated on the basis of 4 Si a.p.f.u., with H2O determined from structure refinement: [(Ca2.89Ba0.01)Σ2.90(Ce0.39La0.18Nd0.14Sm0.02Gd0.03Y0.16Th0.03)Σ1.01Zr0.09]Σ4 [(H2O)2.00Ca0.32Na0.17Al0.10Mn0.04Fe2+0.02☐0.35]Σ3(Ti0.87Nb0.09Zr0.04)Σ1(Si2O7)2[(OH)1.54F0.46]Σ2[(H2O)1.50F0.50]Σ2, Z = 2. The crystal structure of mosandrite is a framework of TS (titanium silicate) blocks; each TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). In the TS block, there are five fully occupied cation sites, two [4]-coordinated Si sites with <Si–O> 1.623 Å , [7]-coordinated MH and AP sites occupied by Ca and REE in the ratio ∼3:1, and one [6]-coordinated Ti-dominant MO(1) site. There are two H2O-dominant H2O-alkali-cation sites. The partly occupied MO(2) site has composition [(H2O)0.5☐0.33Na0.17], ideally [(H2O)0.5☐0.5] p.f.u. The MO(3) site has ideal composition [(H2O)1.5Ca0.5] p.f.u. In the O sheet, the XOM and XOA anion sites have compositions [(OH)1.54F0.46] (XOM) and [(H2O)1.50F0.50] (XOA), ideally (OH)2 and (H2O)2 p.f.u. The MH and AP polyhedra and Si2O7 groups constitute the H sheet that is completely ordered. In the O sheet, MO(1) octahedra are long-range ordered whereas H2O and OH groups and alkali cations Na and Ca are long-range disordered. Two SRO (short-range ordered) arrangements have been proposed for the O sheet: (1) Na [MO(2)], Ca2 [MO(3)] and F4[XOM and XOA anion sites]; (2) 2 H2O [MO(2)] and MO(3)] and (OH)2 and (H2O)2 [XOM and XOA]. Linkage of H and O sheets occurs mainly via common vertices of MH polyhedra and Si2O7 groups and MO(1) octahedra. Two adjacent TS blocks are related by the glide plane cy. Mosandrite is an H2O- and OH-bearing Na- and Ca-depleted analogue of rinkite, ideally (Ca3REE)Na(NaCa) Ti(Si2O7)2(OF)F2. Mosandrite and rinkite are related by the following substitution at the MO(2,3) and XO(M,A) sites in the O sheet: M[(H2O)2 + ☐0.5] + X[(OH)–2 + (H2O)2] ↔ M[Na+2 + Ca2+0.5] + X[(OF)3– + (F2)2–].

Crystal-liquid partition coefficients for pyroxene, spinels, and melilite, in slags

1983 ◽  
Vol 47 (344) ◽  
pp. 335-345 ◽  
Author(s):  
E. Wearing
Keyword(s):  
Crystal Structure ◽  
Electron Microprobe ◽  
Partition Coefficients ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Analytical Data ◽  
Minor Element ◽  
Minor Elements ◽  
Metallurgical Slags

AbstractThe chemistry of spinels, plagioclase, and iron-rich, normally zoned pyroxene and melilite from some metallurgical slags has been investigated by electron microprobe analysis. Minor element partition coefficients, some of which are composition-dependent, have been calculated from the analytical data. The pyroxene/liquid partition coefficients range from 4.03 to 0.03 in the order Ti/Zr, Al, Mn, Zn, Ba, Sn, Na, reflecting increasing incompatibility. The spinel/liquid partition coefficients range from 40.89 to 0.02 but in the order Ti, Ni, Mg/Zn, Al, Mn, Cu, Sn, Zr. However, Sn becomes very compatible when the pyroxene and spinels crystallize in association with cassiterite. Melilite greatly discriminates against the incorporation of minor elements into its crystal structure. The crystallization of these phases produces residual liquids enriched in Na, Mn, Zn, Sn, Ba, W, and Pb.

scholarly journals The chemistry and structure of redledgeite

1986 ◽  
Vol 50 (358) ◽  
pp. 709-715 ◽  
Author(s):  
B. M. Gatehouse ◽  
G. C. Jones ◽  
A. Pring ◽  
R. F. Symes
Keyword(s):  
Crystal Structure ◽  
Phase Space ◽  
Electron Diffraction ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Cation Ordering ◽  
Calculated Density ◽  
Space Group ◽  
Type Phase

AbstractTwo distinct habits of redledgeite are described: small black bipyramidal crystals and yellow-green fibres. The mineral is a Ba-Cr-Ti oxide rather than a Mg-Cr-Ti oxide as previously supposed. Electron microprobe analysis gave Ba1.10(Cr1.82Ti5.95 Fe0.10V0.08)Σ7.95O16 and Ba1.27(Cr2.48Ti5.49Fe0.02)Σ7.99 O16 for the black and yellow-green forms respectively. The mineral is a monoclinic hollandite-type phase, space group I2/m, with a = 10.129(2); b = 2.959(1); c = 10.135(2) Å; β = 90.05(11)° and Z = 1; calculated density for the black form is 4.413 g cm−3. The crystal structure was refined to R 6.3%, Rw 7.4% using 1017 reflections with F > 3σ(F) from a set of 1062 unique reflections. Electron diffraction studies revealed weak superlattice reflections, with a period of 2.24b due to tunnel cation ordering.

Sign in / Sign up

Export Citation Format

Share Document