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

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.

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Crystal chemistry of natural layered double hydroxides: 4. Crystal structures and evolution of structural complexity of quintinite polytypes from the Kovdor alkaline-ultrabasic massif, Kola peninsula, Russia

Mineralogical Magazine ◽

10.1180/minmag.2017.081.046 ◽

2018 ◽

Vol 82 (2) ◽

pp. 329-346 ◽

Cited By ~ 8

Author(s):

Elena S. Zhitova ◽

Sergey V. Krivovichev ◽

Viktor N. Yakovenchuk ◽

Gregory Yu. Ivanyuk ◽

Yakov A. Pakhomovsky ◽

...

Keyword(s):

Crystal Structure ◽

Structural Information ◽

Structural Complexity ◽

Configurational Entropy ◽

Direct Methods ◽

Stacking Sequence ◽

Layer Stacking ◽

Complete Layer ◽

Double Hydroxide ◽

Double Hydroxides

AbstractTwo quintinite polytypes, 3R and 2T, which are new for the Kovdor alkaline-ultrabasic complex, have been structurally characterized. The crystal structure of quintinite-2T was solved by direct methods and refined to R1 = 0.048 on the basis of 330 unique reflections. The structure is trigonal, P$\bar 3$c1, a = 5.2720(6), c = 15.113(3) Å and V = 363.76(8) Å3. The crystal structure consists of [Mg2Al(OH)6]+ brucite-type layers with an ordered distribution of Mg2+ and Al3+ cations according to the $\sqrt 3 $ × $\sqrt 3 $ superstructure with the layers stacked according to a hexagonal type. The complete layer stacking sequence can be described as …=Ab1C = Cb1A=…. The crystal structure of quintinite-3R was solved by direct methods and refined to R1 = 0.022 on the basis of 140 unique reflections. It is trigonal, R$\bar 3$m, a = 3.063(1), c = 22.674(9) Å and V = 184.2(1) Å3. The crystal structure is based upon double hydroxide layers [M2+,3+(OH)2] with disordered distribution of Mg, Al and Fe and with the layers stacked according to a rhombohedral type. The stacking sequence of layers can be expressed as …=АB = BC = CA=… The study of morphologically different quintinite generations grown on one another detected the following natural sequence of polytype formation: 2H → 2T → 1M that can be attributed to a decrease of temperature during crystallization. According to the information-based approach to structural complexity, this sequence corresponds to the increasing structural information per atom (IG): 1.522 → 1.706 → 2.440 bits, respectively. As the IG value contributes negatively to the configurational entropy of crystalline solids, the evolution of polytypic modifications during crystallization corresponds to the decreasing configurational entropy. This is in agreement with the general principle that decreasing temperature corresponds to the appearance of more complex structures.

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Crystal chemistry of natural layered double hydroxides. 3. The crystal structure of Mg,Al-disordered quintinite-2H

Mineralogical Magazine ◽

10.1180/minmag.2010.074.5.841 ◽

2010 ◽

Vol 74 (5) ◽

pp. 841-848 ◽

Cited By ~ 22

Author(s):

E. S. Zhitova ◽

V. N. Yakovenchuk ◽

S. V. Krivovichev ◽

A. A. Zolotarev ◽

Y. A. Pakhomovsky ◽

...

Keyword(s):

Direct Methods ◽

Area Detector ◽

System A ◽

Layer Stacking ◽

Plate Area ◽

Higher Temperature ◽

Diffraction Patterns ◽

Double Hydroxide ◽

Double Hydroxides ◽

Alkaline Massif

AbstractTwo crystals of Mg, Al-disordered quintinite-2H (Q1 and Q2), [Mg4Al2(OH)12](CO3)(H2O)3, from the Kovdor alkaline massif, Kola peninsula, Russia, have been characterized chemically and structurally. Both crystals have hexagonal symmetry, P63/mcm, a = 3.0455(10)/3.0446(9), c = 15.125(7)/15.178(5) Å, V = 121.49(8)/121.84(6) Å3. The structures of the two crystals have been solved by direct methods and refined to R1 = 0.046 and 0.035 on the basis of 76 and 82 unique observed reflections for Q1 and Q2, respectively. Diffraction patterns obtained using an image-plate area detector showed the almost complete absence of superstructure reflections which would be indicative of the Mg-Al ordering in metal hydroxide layers, as has been observed recently for other quintinite polytypes. The crystal structures are based on double hydroxide layers [M(OH)2] with an average disordered distribution of Mg2+ and Al3+ cations. Average <M–OH> bond lengths for the metal site are 2.017 and 2.020 Åfor Q1 and Q2, respectively, and are consistent with a highly Mg-Al disordered, average occupancy. The layer stacking sequence can be expressed as …=AC=CA=…, corresponding to a Mg-Al-disordered 2H polytype of quintinite. The observed disorder is probably the result of a relatively high temperature of formation for the Q1 and Q2 crystals compared to ordered polytypes. This suggestion is in general agreement with the previous observations which demonstrated, for the Mg-Al system, a higher-temperature regime of formation of the hexagonal (or pseudo-hexagonal in the case of quintinite-2H-3c) 2H polytype in comparison to the rhombohedral (or pseudo-rhombohedral in the case of quintinite-1M) 3R polytype.

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Crystal chemistry of natural layered double hydroxides. 2. Quintinite-1M: first evidence of a monoclinic polytype in M2+-M3+ layered double hydroxides

Mineralogical Magazine ◽

10.1180/minmag.2010.074.5.833 ◽

2010 ◽

Vol 74 (5) ◽

pp. 833-840 ◽

Cited By ~ 22

Author(s):

S. V. Krivovichev ◽

V. N. Yakovenchuk ◽

E. S. Zhitova ◽

A. A. Zolotarev ◽

Y. A. Pakhomovsky ◽

...

Keyword(s):

Layered Double Hydroxides ◽

Direct Methods ◽

Monoclinic Space Group ◽

Stacking Sequence ◽

Trivalent Metal ◽

Diffuse Intensity ◽

Layer Stacking ◽

Complete Layer ◽

Double Hydroxides ◽

Alkaline Massif

AbstractQuintinite-1M, [Mg4Al2(OH)12](CO3)(H2O)3, is the first monoclinic representative of both synthetic and natural layered double hydroxides (LDHs) based on octahedrally coordinated di- and trivalent metal cations. It occurs in hydrothermal veins in the Kovdor alkaline massif, Kola peninsula, Russia. The structure was solved by direct methods and refined to R1 = 0.031 on the basis of 304 unique reflections. It is monoclinic, space group C2/m, a = 5.266(2), b = 9.114(2), c = 7.766(3) Å, β = 103.17(3)°, V = 362.9(2) Å3. The diffraction pattern of quintinite-1M contains sharp reflections corresponding to the layer stacking sequence characteristic of the 3R rhombohedral polytype, and rows of weak superlattice reflections superimposed upon a background of streaks of modulated diffuse intensity parallel to c*. These superlattice reflections indicate the formation of a 2-D superstructure due to Mg-Al ordering. The structure consists of ordered metal hydroxide layers and a disordered interlayer. As the unit cell contains exactly one layer, the polytype nomenclature dictates that the mineral be called quintinite-1M. The complete layer stacking sequence can be described as …=Ac1B=Ba1C=Cb1A=… Quintinite-1M is isostructural with the monoclinic polytype of [Li2Al4(OH)12](CO3)(H2O)3.

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Zincalstibite-9R: the first nine-layer polytype with the layered double hydroxide structure-type

Mineralogical Magazine ◽

10.1180/minmag.2012.076.5.01 ◽

2012 ◽

Vol 76 (5) ◽

pp. 1337-1345 ◽

Cited By ~ 13

Author(s):

S. J. Mills ◽

A. G. Christy ◽

A. R. Kampf ◽

R. M. Housley ◽

G. Favreau ◽

...

Keyword(s):

Crystal Structure ◽

Layered Double Hydroxide ◽

Structure Type ◽

Refractive Indices ◽

Stacking Sequence ◽

Oh Groups ◽

Layer Stacking ◽

Periodic Layer ◽

Double Hydroxide ◽

The Ideal

AbstractZincalstibite-9R, a new polytype in the hydrotalcite supergroup is reported from the Monte Avanza mine, Italy. It occurs as pale blue curved disc-like tablets flattened on {001} intergrown to form rosettes typically less than 50 μm in diameter, with cyanophyllite and linarite in cavities in baryte. Zincalstibite-9R is uniaxial (–), with refractive indices ω = 1.647(2) and ε = 1.626(2) measured in white light. The empirical formula (based on 12 OH groups) is (Zn1.092+Cu0.872+Al0.04)Σ2.00Al1.01(Sb0.975+Si0.02)Σ0.99(OH)12, and the ideal formula is (Zn,Cu)2Al(OH)6[Sb(OH)6]. Zincalstibite-9R crystallizes in space group R, with a = 5.340(2), c = 88.01(2) Å, V = 2173.70(15) Å3 and Z = 9. The crystal structure was refined to R1 = 0.0931 for 370 unique reflections [Fo > 4σ(F)] and R1 = 0.0944 for all 381 unique reflections. It has the longest periodic layer stacking sequence for a layered double hydroxide compound reported to date.

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Farneseite, a new mineral of the cancrinite - sodalite group with a 14-layer stacking sequence: occurrence and crystal structure

European Journal of Mineralogy ◽

10.1127/0935-1221/2005/0017-0839 ◽

2006 ◽

Vol 17 (6) ◽

pp. 839-846 ◽

Cited By ~ 17

Author(s):

Fernando Cá mara ◽

Fabio Bellatreccia ◽

Giancarlo Della Ventura ◽

Annibale Mottana

Keyword(s):

Crystal Structure ◽

New Mineral ◽

Stacking Sequence ◽

Layer Stacking

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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

Mineralogical Magazine ◽

10.1180/minmag.2017.081.015 ◽

2017 ◽

Vol 81 (6) ◽

pp. 1533-1550 ◽

Cited By ~ 4

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.

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CARBOBYSTRITE, Na8[Al6Si6O24](CO3){middle dot}4H2O, A NEW CANCRINITE-GROUP MINERAL SPECIES FROM THE KHIBINA ALKALINE MASSIF, KOLA PENINSULA, RUSSIA: DESCRIPTION AND CRYSTAL STRUCTURE

The Canadian Mineralogist ◽

10.3749/canmin.48.2.291 ◽

2010 ◽

Vol 48 (2) ◽

pp. 291-300 ◽

Cited By ~ 8

Author(s):

A. P. Khomyakov ◽

F. Camara ◽

E. Sokolova

Keyword(s):

Crystal Structure ◽

Kola Peninsula ◽

Mineral Species ◽

Group Mineral ◽

Alkaline Massif

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Odigitriaite, CsNa5Ca5[Si14B2O38]F2, a new caesium borosilicate mineral from the Darai-Pioz alkaline massif, Tajikistan: Description and crystal structure

Mineralogical Magazine ◽

10.1180/minmag.2016.080.074 ◽

2017 ◽

Vol 81 (1) ◽

pp. 113-122 ◽

Cited By ~ 1

Author(s):

Atali A. Agakhanov ◽

Leonid A. Pautov ◽

Elena Sokolova ◽

Frank C. Hawthorne ◽

Vladimir Yu Karpenko ◽

...

Keyword(s):

Crystal Structure ◽

Double Layer ◽

Direct Methods ◽

Double Layers ◽

Monoclinic Space Group ◽

X Ray Diffraction ◽

Calculated Density ◽

X Ray ◽

Mohs Hardness ◽

Alkaline Massif

AbstractOdigitriaite, a new Cs, Na, Ca borosilicate mineral, was discovered in moraine adjacent to the Darai-Pioz alkaline massif in the upper reaches of the Darai-Pioz river at the intersection of the Turkestansky, Zeravshansky and Alaisky mountain ridges, Tajikistan. It occurs as irregular thin flakes associated with quartz, pectolite, baratovite, fluorite, pekovite, polylithionite, aegirine, leucosphenite, pyrochlore, neptunite, reedmergnerite, mendeleevite-(Ce), zeravshanite and sokolovaite. It is colourless with a white streak, is translucent and has a vitreous lustre; it does not fluoresce under ultraviolet light. Odigitriaite is brittle with an uneven fracture and a Mohs hardness of 5. The calculated density is 2.80(2) g/cm3. The indices of refraction are α = 1.502, β = 1.564, γ = 1.576; 2Vobs = 46(2)°, dispersion is weak r > v, and there is no pleochroism. The chemical composition is as follows (electron microprobe, H2O calculated from structure): SiO2 55.30, Al2O3 0.09, Y2O3 0.44, MnO 0.94, FeO 0.10, PbO 0.21, K2O 0.01 Cs2O 8.36, B2O3 4.75, H2O 0.37, F 1.74, O = F2 –0.74, total 99.43 wt.%. The empirical formula of odigitriaite is Cs0.90Na5.12Ca4.68Mn0.20Y0.06Fe0.02Pb0.01[Si13.92Al0.03B2.06O38]F1.39(OH)0.62. The end-member formula is CsNa5Ca5[Si14B2O38]F2. The strong reflections in the powder X-ray diffraction pattern are: [(d, Å), (I, %), (hkl)]: 5.45 (25) (1 1 3), 4.66 (33) (3 1 1), 4.40 (26) (0 2 2), 4.10 (36) (3 1 3), 3.95 (25) (3̄ 1 3), 2.85 (31) (2 2 2), 2.68 (40) (0 0 6), 3.62 (45) (0 2 4), 3.35 (100) (2̄ 2 4), 3.31 (30) (3̄ 1 5), 3.25 (35) (4 0 4), 3.04 (60) (4̄ 2 2), 2.925 (22) (4̄ 2 3), 1.813 (23) (9 1 0). Odigitriaite is monoclinic, space group C2/c, a = 16.652(5), b = 9.598 (3), c = 22.120(7) Å, β= 92.875(14)°, V = 3530.9(1.9) Å3, Z = 4. The crystal structure of odigitriaite was solved by direct methods and refined to an R1 value of 2.75% based on single-crystal X-ray data. It is a double-layer sheet-borosilicate mineral; Cs and Na are intercalated within the double-layer sheet, and the double layers are linked by interstitial Ca and Na atoms.

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