scholarly journals New Data on the Isomorphism in Eudialyte-Group Minerals. 2. Crystal-Chemical Mechanisms of Blocky Isomorphism at the Key Sites

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 720 ◽  
Author(s):  
Ramiza K. Rastsvetaeva ◽  
Nikita V. Chukanov
Keyword(s):  
Valence State ◽  
Crystal Chemical ◽  
Eudialyte Group ◽  
Coordination Numbers ◽  
Chemical Mechanisms ◽  
Complex Mechanisms ◽  
Key Sites ◽  
Heteropolyhedral Framework

The review considers various complex mechanisms of isomorphism in the eudialyte-group minerals, involving both key positions of the heteropolyhedral framework and extra-framework components. In most cases, so-called blocky isomorphism is realized when one group of atoms and ions is replaced by another one, which is accompanied by a change in the valence state and/or coordination numbers of cations. The uniqueness of these minerals lies in the fact that they exhibit ability to blocky isomorphism at several sites of high-force-strength cations belonging to the framework and at numerous sites of extra-framework cations and anions.

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.

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.

Crystal Chemical Studies by X-Ray Fluorescence

1958 ◽  
Vol 2 ◽  
pp. 239-245 ◽  
Author(s):  
Eugene W. White ◽  
Herbert A. McKinstry ◽  
Thomas F. Bates
Keyword(s):  
Valence State ◽  
Crystal Chemical ◽  
Characteristic Radiation ◽  
X Ray ◽  
Chemical Studies ◽  
Titanium Vanadium

AbstractThe wavelength of the characteristic X-radiation for the lighter elements is not constant but is a function of valence state and to a much lesser extent is a function of co-ordination number.Commercially available X-ray fluorescence equipment is used in detecting shifts in the characteristic radiation for aluminum, sulfur, chlorine, titanium, vanadium and iron. The greatest shift is found in the case of chlorine where, using the NaCl analyzer, a shift of nearly 0.2° 2 θ is obtained in going from the Cl− in cholorides to the Cl+7 in the perchloratc. The wavelength of the Al+3Kα varies slightly as a function of co-ordination number.Examples are given for using these phenomena in studying minerals and other compounds. The feasibility of extending the study to both heavier and lighter elements is explored.

Crystal structure and crystal-chemical features of a new Ti-rich member of the eudialyte family

1999 ◽  
Vol 214 (5) ◽  
Author(s):  
R. K. Rastsvetaeva ◽  
A. P. Khomyakov ◽  
G. Chapuis
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Chemical ◽  
Single Crystal Diffraction ◽  
Eudialyte Group ◽  
X Ray ◽  
Trigonal Structure

AbstractThe trigonal structure of a new member of the eudialyte group was established from X-ray single-crystal diffraction,

CRYSTAL HABIT OF MINERALS — A CRYSTAL CHEMICAL APPROACH

2007 ◽  
Vol 21 (06) ◽  
pp. 871-883
Author(s):  
J. HAUCK ◽  
K. MIKA
Keyword(s):  
High Density ◽  
The Self ◽  
Crystal Habit ◽  
Crystal Chemical ◽  
Coordination Numbers ◽  
Chemical Approach ◽  
Bulk Structure ◽  
Cl Atoms

Homogeneous particles A like carbon atoms in diamond, CO 3 ions in CaCO 3, or sulfur molecules in sulfur with different A–A interactions are ordered in such a way that the bulk structure can be characterized by the self-coordination numbers T i, i = 1-3, of nearest, second, and third neighbors. There are about 500 sets with increased Ti values and about 500 sets with reduced Ti values, which can be obtained from characteristic lattice complexes. The different sets with increased Ti values are characterized by S, L, or R for sphere, layer, or rod packing. Two or more particles A, B, C, etc., can belong to the same set like Na and Cl atoms in NaCl or different sets like Ca and F atoms in CaF 2. The Dirichlet domains of A and B ( CaF 2) or A + B ( NaCl ) are approaches to the morphological lattices (cubes or rhombododecahedra). Planes with a high density of A positions and thus low h k l values like the {111} planes of octahedra are derived from Bravais' theory. The morphological lattices of layer or rod packings are layers or rods because of the increased densities of A in layers or rods.

Normal to inverse transition in martian spinel: Understanding the interplay between chromium, vanadium, and iron valence state partitioning through a crystal-chemical lens

2015 ◽  
Vol 100 (10) ◽  
pp. 2018-2025 ◽  
Author(s):  
James J. Papike ◽  
Paul V. Burger ◽  
Aaron S. Bell ◽  
Charles K. Shearer ◽  
Loan Le ◽  
...  
Keyword(s):  
Valence State ◽  
Crystal Chemical ◽  
Iron Valence ◽  
Inverse Transition

scholarly journals New Data on the Isomorphism in Eudialyte-Group Minerals. 1. Crystal Chemistry of Eudialyte-Group Members with Na Incorporated into the Framework as a Marker of Hyperagpaitic Conditions

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 587 ◽  
Author(s):  
Ramiza K. Rastsvetaeva ◽  
Nikita V. Chukanov ◽  
Igor V. Pekov ◽  
Christof Schäfer ◽  
Konstantin V. Van
Keyword(s):  
Crystal Chemistry ◽  
Igneous Rocks ◽  
Partial Substitution ◽  
New Mineral ◽  
Eudialyte Group ◽  
New Mineral Species ◽  
Two Samples ◽  
Group Members ◽  
Key Sites ◽  
Simplified Formula

A review of the crystal chemistry of Fe-deficient eudialyte-group minerals is given. Specific features of cation distribution over key sites in the crystal structure, including partial substitution of Fe2+ with Na, Mn and Zr at the M2 site are discussed. It is concluded that Na-dominant (at the M2 site) eudialyte-group members (M2Na-EGMs) are markers of specific kinds of specific peralkaline (hyperagpaitic) igneous rocks and pegmatites. New data are obtained on the chemical composition, IR spectra and crystal chemistry for two samples of M2Na-EGMs with disordered M1 cations, which are a potentially new mineral species with the simplified formula (Na,H2O)15Ca6Zr3[Na2(Fe,Zr)][Si26O72](OH)2Cl·nH2O.

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