Vittinkiite, MnMn4[Si5O15], a member of the rhodonite group with a long history: definition as a mineral species

2020 ◽  
pp. 1-12
Author(s):  
Nadezhda V. Shchipalkina ◽  
Igor V. Pekov ◽  
Nikita V. Chukanov ◽  
Natalia V. Zubkova ◽  
Dmitry I. Belakovskiy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mineral Species ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Triclinic Space Group ◽  
Group Mineral ◽  
Coordination Numbers ◽  
The Relationship ◽  
Mn Oxides

Abstract The rhodonite-group mineral with the idealised, end-member formula MnMn4[Si5O15] and the crystal chemical formula VIIM(5)MnVIM(1–3)Mn3VIIM(4)Mn[Si5O15] (Roman numerals indicate coordination numbers) is defined as a valid mineral species named vittinkiite after the type locality Vittinki (Vittinge) mines, Isokyrö, Western and Inner Finland Region, Finland. Vittinkiite is an isostructural analogue of rhodonite, ideally CaMn4[Si5O15], with Mn2+ > Ca at the M(5) site. Besides Vittinki, vitiinkiite was found in more than a dozen rhodonite deposits worldwide, however, it is significantly less common in comparison with rhodonite. The mineral typically forms pink to light pink massive, granular aggregates and is associated with quartz, rhodonite, tephroite, pyroxmangite and Mn oxides. Vittinkiite is optically biaxial (+), with α = 1.725(4), β = 1.733(4), γ = 1.745(5) and 2Vmeas = 75(10)° (589 nm). The chemical composition of the holotype (wt.%, electron microprobe) is: MgO 0.52, CaO, 0.93, MnO 51.82, FeO 1.26, ZnO 0.11, SiO2 46.48, total 101.12. The empirical formula calculated based on 15 O apfu is Mn4.71Ca0.11Fe0.11Mg0.08Zn0.01Si4.99O15. Vittinkiite is triclinic, space group P $\bar{1}$ , with a = 6.6980(3), b = 7.6203(3), c = 11.8473(5) Å, α = 105.663(3), β = 92.400(3), γ = 94.309(3)°, V = 579.38(7) Å3 and Z = 2. The crystal structure is solved on a single crystal to R1 = 3.85%. Polymorphism of MnSiO3 (rhodonite-, pyroxmangite-, garnet- and clinopyroxene-type manganese metasilicates) is discussed, as well as the relationship between vittinkiite and pyroxmangite, ideally Mn7[Si7O21], and the application of infrared spectroscopy for the identification of manganese pyroxenoids.

Coquandite, Sb6+xO8+x(SO4)(OH)x·(H2O)1–x (x = 0.3), from the Cetine mine, Tuscany, Italy: crystal structure and revision of the chemical formula

2014 ◽  
Vol 78 (4) ◽  
pp. 871-888
Author(s):  
L. Bindi ◽  
C. Biagioni ◽  
L. Ceccantini ◽  
M. Batoni ◽  
S. Menchetti
Keyword(s):  
Crystal Structure ◽  
Scientific Literature ◽  
Crystal Chemical ◽  
Anisotropic Model ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Form Complex ◽  
Triclinic Space Group ◽  
Bonding System ◽  
Sulfate Hydrate

AbstractThe crystal structure of the mineral coquandite, a rare Sb oxy-sulfate hydrate, was solved using intensity data collected from a crystal from the Cetine mine, Tuscany, Italy. This study revealed that the structure is triclinic, space group P, with a = 11.4292(5), b = 29.772(1), c = 11.2989(5) Å, α = 91.152(3), β = 119.266(4), γ = 92.624(3)° and V = 3346.4(2) Å3. The refinement of an anisotropic model led to an R index of 0.0347 for 21,061 independent reflections. Thirty-two Sb sites, five S sites and 67 oxygen sites occur in the crystal structure of coquandite. Sb atoms display the characteristic SbO3E and SbO4E coordinations whereas S fills (SO4) tetrahedral groups. These atoms are arranged in five symmetry-independent layers perpendicular to b*. Four of them and their centrosymmetrical counterparts form complex modules stacked along b* and bonded through two Sb atoms and H bonds. The complex H bonding system in the structure is discussed. On the basis of information gained from this characterization, the crystal-chemical formula was revised according to the structural results, yielding Sb6+xO8+x(SO4)(OH)x·(H2O)1–x (Z = 10) with x = 0.3 instead of Sb6O8(SO4)·H2O (Z = 12) as reported previously. A recalculation of the chemical data listed in the scientific literature for coquandite according to the structural results obtained here leads to a satisfactory agreement.

Crystal structure of KBSi3O8 isostructural with danburite

1993 ◽  
Vol 57 (386) ◽  
pp. 157-164 ◽  
Author(s):  
Mitsuyoshi Kimata
Keyword(s):  
Crystal Structure ◽  
Direct Method ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
3 Dimensional ◽  
Tetrahedral Sites ◽  
Structural Types ◽  
Coupled Substitution ◽  
Insight Into

AbstractThe crystal structure of KBSi3O8 (orthorhombic, Pnam, with a = 8.683(1), b = 9.253(1), c = 8.272(1) Å,, V = 664.4(1) Å3, Z = 4) has been determined by the direct method applied to 3- dimensional rcflection data. The structure of a microcrystal with the dimensions 20 × 29 × 37 μm was refined to an unweightcd residual of R = 0.031 using 386 non-zero structure amplitudes. KBSi3O8 adopts a structure essentially different from recdmergneritc NaBSi3O8, with the low albite (NaAlSi3O8) structure, and isotypic with danburite CaB2Si2Os which has the same topology as paracelsian BaAl2Si2O8. The chenfical relationship between this sample and danburitc gives insight into a new coupled substitution; K+ + Si4+ = Ca2+ + B3+ in the extraframework and tetrahedral sites. The present occupancy refinement revealed partial disordering of B and Si atoms which jointly reside in two kinds of general equivalent points, T(1) and T(2) sites. Thus the expanded crystal-chemical formula can be written in the form K(B0.44Si0.56)2(B0.06Si0.94)2O8The systematic trend among crystalline compounds with the M+T3+T4+3O8 formula suggests that they exist in one of four structural types; the feldspar structures with T3+/T4+ ordered and/or disordered forms, and the paracelsian and the hollandite structures.

Al analogue of chayesite from a lamproite of Cancarix, SE Spain, and its crystal structure

2020 ◽  
Vol 196 (3) ◽  
pp. 193-198
Author(s):  
Natalia V. Zubkova ◽  
Nikita V. Chukanov ◽  
Christof Schäfer ◽  
Konstantin V. Van ◽  
Igor V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Empirical Formula ◽  
Structure Refinement ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
X Ray Diffraction ◽  
Se Spain ◽  
X Ray

Al analogue of chayesite (with Al > Fe3+) was found in a lamproite from Cancarix, SE Spain. The mineral forms green thick-tabular crystals up to 0.4 mm across in cavities. The empirical formula derived from EMP measurements and calculated on the basis of 17 Mg + Fe + Al + Si apfu is (K0.75 Na0.20 Ca0.11)Mg3.04 Fe0.99 Al1.18 Si11.80 O30. The crystal structure was determined from single crystal X-ray diffraction data ( R = 2.38%). The mineral is hexagonal, space group P 6/ mcc, a = 10.09199(12), c = 14.35079(19) Å, V = 1265.78(3) Å3, Z = 2. Fe is predominantly divalent. Al is mainly distributed between the octahedral A site and the tetrahedral T 2 site. The crystal chemical formula derived from the structure refinement is C (K0.73 Na0.16 Ca0.11)B (Na0.02)4 A(Mg0.42 Al0.29 Fe0.29)2 T 2(Mg0.71 Fe0.16 Al0.13)3 T 1(Si0.985 Al0.015)12 O30.

The crystal structure of nonmetamict Nb-rich zirconolite-3T from the Eifel paleovolcanic region, Germany

2018 ◽  
Vol 233 (7) ◽  
pp. 463-468 ◽  
Author(s):  
Natalia V. Zubkova ◽  
Nikita V. Chukanov ◽  
Igor V. Pekov ◽  
Bernd Ternes ◽  
Willi Schüller ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Empirical Formula ◽  
Structural Model ◽  
Crystal Chemical ◽  
Single Crystal Xrd ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Abstract The crystal structure of a Nb-rich zirconolite-3T from the Laach Lake volcano, Eifel, Germany, was studied by single-crystal XRD (R=0.0295). The mineral is trigonal, P3121; unit-cell dimensions are: a=7.3095(2), c=16.9604(5) Å, V=784.78(4) Å3. The empirical formula based on 14 O atoms (Z=3) is Ca1.28Ce0.31La0.14Nd0.12Pr0.06Th0.16 Zr1.94Hf0.04Ti1.74Nb1.22Fe0.72Mn0.28O14. The crystal-chemical formula based upon the structural model is: VIII(Ca0.70 Ce0.30)VIII(Ca0.58Ce0.32Th0.10)VII(Zr0.88Th0.04Hf0.02□0.06)2VII(□0.94 Zr0.06)2VI(Ti0.72Nb0.26Zr0.02)VI(Ti0.50Nb0.47Zr0.03)2IV(Fe0.355 Mn0.145)2O14 (Z=3).

Metavivianite, Fe2+Fe3+2(PO4)2(OH)2·6H2O: new data and formula revision

2012 ◽  
Vol 76 (3) ◽  
pp. 725-741 ◽  
Author(s):  
N. V. Chukanov ◽  
R. Scholz ◽  
S. M. Aksenov ◽  
R. K. Rastsvetaeva ◽  
I. V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gas Chromatography ◽  
Optical Properties ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Homogeneous Sample ◽  
X Ray ◽  
Composition Structure ◽  
First Time

AbstractThe composition, structure, X-ray powder diffraction pattern, optical properties, density, infrared, Raman and Mössbauer spectra, and thermal properties of a homogeneous sample of metavivianite from the Boa Vista pegmatite, near Galiléia, Minas Gerais, Brazil are reported for the first time. Metavivianite is biaxial (+) with α = 1.600(3), β = 1.640(3), γ = 1.685(3) and 2Vmeas= 85(5)°. The measured and calculated densities are Dmeas= 2.56(2) and Dcalc= 2.579 g cm–3. The chemical composition, based on electronmicroprobe analyses, Mössbauer spectroscopy (to determine the Fe2+:Fe3+ratio) and gas chromatography (to determine H2O) is MgO 0.70, MnO 0.92, FeO 17.98, Fe2O326.60, P2O528.62, H2O 26.5; total 101.32 wt.%. The empirical formula is (Fe3+1.64Fe2+1.23Mg0.085Mn0.06)Σ3.015(PO4)1.98(OH)1.72·6.36H2O. Metavivianite is triclinic, P1̄, a = 7.989(1), b = 9.321(2), c = 4.629(1) Å, α = 97.34(1), β = 95.96(1), γ = 108.59(2)°, V = 320.18(11) Å3and Z = 1. The crystal structure was solved using a single-crystal techniques to an agreement index R = 6.0%. The dominant cations in the independent sites are Fe2+and Fe3+, with multiplicities of 1 and 2, respectively. The simplified crystal-chemical formula for metavivianite is Fe2+(Fe3+, Fe2+)2(PO4)2(OH,H2O)2·6H2O; the endmember formula is Fe2+Fe3+2(PO4)2(OH)2·6H2O, which is dimorphous with ferrostrunzite.

Redefinition of coquimbite, AlFe3+3(SO4)6(H2O)12⋅6H2O

2020 ◽  
Vol 84 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Daniela Mauro ◽  
Cristian Biagioni ◽  
Marco Pasero ◽  
Henrik Skogby ◽  
Federica Zaccarini
Keyword(s):  
Crystal Structure ◽  
Chemical Data ◽  
Mineral Species ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Hydrated Sulfate ◽  
Crystal Chemical Data ◽  
Distinct Site ◽  
Apuan Alps

AbstractCoquimbite, AlFe3+3(SO4)6(H2O)12⋅6H2O, was considered as a pure Fe3+ hydrated sulfate. However, previous mineralogical studies pointed out the occurrence of essential Al, occupying a distinct site in the crystal structure of this mineral. Through the critical re-examination of the available literature and new crystal-chemical data collected on a specimen from the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy, the chemical formula of coquimbite has been revised, taking into account the occurrence of Al. Coquimbite has a homeotypic relationship with paracoquimbite, Fe4(SO4)6(H2O)12⋅6H2O; both mineral species belong to the coquimbite group. On the contrary, aluminocoquimbite, Al2Fe2(SO4)6(H2O)12⋅6H2O, has a different topology and does not belong to that group.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XIV. Badalovite, NaNaMg(MgFe3+)(AsO4)3, a member of the alluaudite group

2020 ◽  
Vol 84 (4) ◽  
pp. 616-622
Author(s):  
Igor V. Pekov ◽  
Natalia N. Koshlyakova ◽  
Atali A. Agakhanov ◽  
Natalia V. Zubkova ◽  
Dmitry I. Belakovskiy ◽  
...  
Keyword(s):  
Scoria Cone ◽  
Fissure Eruption ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Xrd Pattern ◽  
Group Mineral ◽  
Tolbachik Volcano ◽  
Mohs Hardness ◽  
Simplified Formula

AbstractThe new alluaudite-group mineral badalovite was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hematite, tenorite, cassiterite, johillerite, nickenichite, calciojohillerite, bradaczekite, metathénardite, aphthitalite, langbeinite, calciolangbeinite, sanidine, fluorophlogopite, fluoborite, tilasite, anhydrite, pseudobrookite, sylvite, halite, lammerite, urusovite, ericlaxmanite, arsmirandite, svabite, krasheninnikovite, euchlorine, wulffite and alumoklyuchevskite. Badalovite forms oblique-angled prismatic crystals up to 1 mm × 1 mm × 5 mm, typically combined in groups or crusts up to several hundred cm2 in area. The mineral is transparent, green, grey, yellow or colourless, with vitreous lustre. It is brittle, the Mohs hardness is 3½. Cleavage was not observed, the fracture is uneven. Dcalc is 4.02 g cm–3. Badalovite is optically biaxial (–), α = 1.753(3), β = 1.757(3), γ = 1.758(3) and 2Vmeas. = 50(10)°. Chemical composition (wt.%, electron-microprobe; holotype) is: Na2O 9.23, K2O 0.19, CaO 2.04, MgO 13.78, MnO 0.31, CuO 0.12, ZnO 0.24, Al2O3 0.06, Fe2O3 12.77, TiO2 0.01, SiO2 0.06, P2O5 0.33, V2O5 0.05, As2O5 61.51, SO3 0.02, total 100.72. The empirical formula based on 12 O apfu is Na1.67Ca0.20K0.02Mg1.92Zn0.02Mn0.02Cu0.01Fe3+0.90Al0.01(As3.01P0.03Si0.01)Σ3.05O12. The simplified formula is Na2Mg2Fe3+(AsO4)3. Badalovite is monoclinic, C2/c, a = 11.9034(3), b = 12.7832(2), c = 6.66340(16) Å, β = 112.523(3)°, V = 936.59(4) Å3 and Z = 4. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 6.41(38)(020), 5.505(20)(200), 3.577(23)($\bar{1}$31), 3.523(25)(310), 3.211(46)($\bar{1}$12), 2.911(28)($\bar{2}$22, $\bar{3}$12), 2.765(100)(240, 400) and 2.618(26)($\bar{1}$32). The crystal structure was solved from single-crystal XRD data with an R1 of = 2.49%. Badalovite is isostructural with other alluaudite-group minerals. Its simplified crystal chemical formula is A(1)NaA(1)’□A(2) □A(2)’NaM(1)MgM(2)(Mg0.5Fe3+0.5)2(AsO4)3 (□ – vacancy) and the end-member formula is NaNaMg(MgFe3+)(AsO4)3. The mineral is named in honour of the outstanding mineralogist and geochemist Stepan Tigranovich Badalov (1919–2014).

Analysis of the environment of beryllium, magnesium and alkaline earth atoms in oxygen-containing compounds

1999 ◽  
Vol 55 (2) ◽  
pp. 139-146 ◽  
Author(s):  
V. A. Blatov ◽  
L. V. Pogildyakova ◽  
V. N. Serezhkin
Keyword(s):  
Crystal Structure ◽  
Alkaline Earth ◽  
Organometallic Compounds ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Crystal Chemical ◽  
Coordination Polyhedra ◽  
Coordination Numbers ◽  
Coordination Spheres

About 2100 inorganic and organometallic compounds containing beryllium, magnesium and alkaline earth atoms (M) were investigated with Voronoi–Dirichlet polyhedra (VDPs). It is shown that the coordination numbers (CNs) of the M atoms in MO n coordination polyhedra can be determined by means of VDPs without crystal-chemical radii. The distributions of the M—O distances in the coordination spheres of the M atoms are bimodal for M = Be or Mg and monomodal for the other alkaline earth metals. Beryllium and magnesium coordination polyhedra containing weak M—O contacts were classified by variants of their distortions. It is found that the volume of the domains of the Mg, Ca, Sr and Ba atoms is independent of their CNs at CN \ge 6 (up to 16 for barium). The possibility of using the model of deformable spheres to describe the crystal structure of the compounds investigated is suggested.

Site distribution of Fe2+and Fe3+in the axinite mineral group: New crystal-chemical formula

2004 ◽  
Vol 89 (11-12) ◽  
pp. 1763-1771 ◽  
Author(s):  
Giovanni B. Andreozzi ◽  
Sergio Lucchesi ◽  
Giorgio Graziani ◽  
Umberto Russo
Keyword(s):  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Site Distribution
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