Trigonal variation in the garnet supergroup: the crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, from Kovdor massif, Kola Peninsula, Russia

2021 ◽  
pp. 1-22
Author(s):  
Sergey V. Krivovichev ◽  
Taras L. Panikorovskii ◽  
Victor N. Yakovenchuk ◽  
Ekaterina A. Selivanova ◽  
Gregory Yu. Ivanyuk
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula

Crystal Structure of Niobium-Rich Lomonosovite with Symmetry P1 from the Khibiny Massif (Kola Peninsula)

2020 ◽  
Vol 65 (3) ◽  
pp. 422-427
Author(s):  
R. K. Rastsvetaeva ◽  
V. A. Zaitsev ◽  
I. V. Pekov
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
Khibiny Massif

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.

Crystal chemistry of natural layered double hydroxides. I. Quintinite-2H-3c from the Kovdor alkaline massif, Kola peninsula, Russia

2010 ◽  
Vol 74 (5) ◽  
pp. 821-832 ◽  
Author(s):  
S. V. Krivovichev ◽  
V. N. Yakovenchuk ◽  
E. S. Zhitova ◽  
A. A. Zolotarev ◽  
Y. A. Pakhomovsky ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
Direct Methods ◽  
Stacking Sequence ◽  
Layer Sequence ◽  
Layer Stacking ◽  
Double Hydroxide ◽  
Double Hydroxides ◽  
First Time ◽  
Alkaline Massif

AbstractThe crystal structure of quintinite-2H-3c, [Mg4Al2(OH)12](CO3)(H2O)3, from the Kovdor alkaline massif, Kola peninsula, Russia, was solved by direct methods and refined to an agreement index (R1) of 0.055 for 484 unique reflections with |Fo| ≥ 4σF. The mineral is rhombohedral, R32, a = 5.2745(7), c = 45.36(1) Å. The diffraction pattern of the crystal has strong and sharp Bragg reflections having h–k = 3n and l = 3n and lines of weak superstructure reflections extended parallel to c* and centred at h–k ≠ 3n. The structure contains six layers within the unit cell with the layer stacking sequence of …AC=CA=AC=CA=AC=CA… The Mg and Al atoms are ordered in metal hydroxide layers to form a honeycomb superstructure. The full superstructure is formed by the combination of two-layer stacking sequence and Mg-Al ordering. This is the first time that a long-range superstructure in carbonate-bearing layered double hydroxide (LDH) has been observed. Taking into account Mg-Al ordering, the unique layer sequence can be written as …=Ab1C=Cb1A=Ab2C=Cb2A=Ab3C=Cb3A=… The use of an additional suffix is proposed in order to distinguish between LDH polytypes having the same general stacking sequence but with different c parameters compared with the ‘standard’ polytype. According to this notation, the quintinite studied here can be described as quintinite-2H-3c or quintinite-2H-3c[6R], indicating the real symmetry.

scholarly journals MEGAKALSILITE, A NEW POLYMORPH OF KAlSiO4 FROM THE KHIBINA ALKALINE MASSIF, KOLA PENINSULA, RUSSIA: MINERAL DESCRIPTION AND CRYSTAL STRUCTURE

2002 ◽  
Vol 40 (3) ◽  
pp. 961-970 ◽  
Author(s):  
A. P. Khomyakov ◽  
G. N. Nechelyustov ◽  
E. Sokolova ◽  
E. Bonaccorsi ◽  
S. Merlino ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
Alkaline Massif

scholarly journals Shkatulkalite, a Rare Mineral from the Lovozero Massif, Kola Peninsula: A Re-Investigation

Minerals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 303 ◽  
Author(s):  
Andrey Zolotarev ◽  
Ekaterina Selivanova ◽  
Sergey Krivovichev ◽  
Yevgeny Savchenko ◽  
Taras Panikorovskii ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
General Formula ◽  
Interlayer Space ◽  
Mineral Species ◽  
Lovozero Massif ◽  
Structural Relations ◽  
Alkaline Massif

The crystal structure of shkatulkalite has been solved from the crystal from the Lovozero alkaline massif, Kola Peninsula, Russia. The mineral is monoclinic, P2/m, a = 5.4638(19), b = 7.161(3), c = 15.573(6) Å, β = 95.750(9)°, V = 606.3(4) Å3, R1 = 0.080 for 1551 unique observed reflections. The crystal structure is based upon the HOH blocks consisting of one octahedral (O) sheet sandwiched between two heteropolyhedral (H) sheets. The blocks are parallel to the (001) plane and are separated from each other by the interlayer space occupied by Na1 atoms and H2O groups. The Na2, Na3, and Ti sites are located within the O sheet. The general formula of shkatulkalite can be written as Na5(Nb1−xTix)2(Ti1−yMn2+y)[Si2O7]2O2(OH)2·nH2O, where x + y = 0.5 and x ≈ y ≈ 0.25 for the sample studied. Shkatulkalite belongs to the seidozerite supergroup and is a member of the lamprophyllite group. The species most closely related to shkatulkalite are vuonnemite and epistolite. The close structural relations and the reported observations of pseudomorphs of shkatulkalite after vuonnemite suggest that, at least in some environments, shkatulkalite may form as a transformation mineral species.

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.

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