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Single crystals of the new modification of copper pyrovanadate, δ-Cu2V2O7, were prepared using the chemical vapor transport reaction method. The crystal structure (monoclinic, P21/n, a = 5.0679(3), b = 11.4222(7), c = 9.4462(6) Å, β = 97.100(6)°, V = 542.61(6) Å3, Z = 4) was solved by direct methods and refined to R1 = 0.029 for 1818 independent observed reflections. The crystal structure contains two Cu sites: the Cu1 site in [4 + 2]-octahedral coordination and the Cu2 site in [4 + 1]-tetragonal pyramidal coordination. There are two V5+ sites, both tetrahedrally coordinated by O atoms. Two adjacent V1O4 and V2O4 tetrahedra share the O4 atom to form a V2O7 dimer. The crystal structure of δ-Cu2V2O7 can be described as based upon layers of V2O7 dimers of tetrahedra parallel to the (001) plane and interlined by chains of the edge-sharing Cu1O6 and Cu2O5 polyhedra running parallel to the a axis and arranged in the layers parallel to the (001) plane. The crystal chemical analysis of the three other known Cu2V2O7 polymorphs indicates that, by analogy with δ-Cu2V2O7, they are based upon layers of V2O7 groups interlinked by layers consisting of chains of CuOn coordination polyhedra (n = 5, 6). The crystal structures of the Cu2V2O7 polymorphs can be classified according to the mutual relations between the Cu-O chains, on the one hand, and the V2O7 groups, on the other hand. The analysis of the literature data and physical density values suggests that, at ambient pressure, α- and β-Cu2V2O7 are the low- and high-temperature polymorphs, respectively, with the phase transition point at 706–710 °C. The β-phase (ziesite) may form metastably under temperatures below 560 °C and, under heating, transform into the stable α-phase (blossite) at 605 °C. The δ- and γ-polymorphs have the highest densities and most probably are the high-pressure phases. The structural complexity relations among the polymorphs correspond to the sequence α = β < γ < δ; i.e., the δ phase described herein possesses the highest complexity, which supports the hypothesis about its stability under high-pressure conditions. [ABSTRACT FROM AUTHOR]

The crystal structure, thermal behavior, and vibrational spectra of the anthropogenic analogue of boussingaultite, (NH4)2Mg(SO4)2·6H2O, and its dehydrated counterpart efremovite, (NH4)2Mg2(SO4)3, were studied in detail. The sample from the Chelyabinsk burning coal dumps has the composition of (NH4)1.92(Mg1.02Mn0.01Fe0.01)∑1.04(SO4)2·6H2O and crystallizes in the space group P21/a, with a = 9.3183(4), b = 12.6070(4), c = 6.2054(3) Å, β = 107.115(5)°, V = 696.70(5) Å3 (at 20 °C), Z = 2. The thermal evolution steps are as follows: boussingaultite (NH4)2Mg(SO4)2·6H2O (25–90 °C) → X-ray amorphous phase (100–150 °C) → efremovite (NH4)2Mg2(SO4)3 (160–340 °C) → MgSO4 Cmcm + Pbnm (340–580 °C) → MgSO4 Pbnm (580–700 °C). Thermal expansion is anisotropic, with the coefficients (×106 °C−1) α11 = 52(2), α22 = 68(2), α33 = –89(3), and αv = 31(3) at T = –123 °C; and α11 = 53(2), α22 = 67(2), α33 = 15(1), and αv = 136(3) at T = 60 °C. The maximal thermal expansion is along the b-axis and is due to straightening of corrugated pseudolayers (within the ab plane) of Mg(H2O)6 octahedra and SO4 tetrahedra with NH4 groups in the interlayer space. Vibrational spectroscopy outlines the general trend of dehydration and deammonization as the difference in the temperature intervals of these transformation steps allows separation of O–H and N–H vibrations in the process of dehydration by infrared and Raman spectroscopy. The intermediate partially dehydrated modification of boussingaultite was detected by in situ Raman spectroscopy at 110 °C that may correspond to ammonium leonite. [ABSTRACT FROM AUTHOR]

'Rhythmite', Ca29(SiO4)8Cl26, an anthropogenic calcium chloride silicate from the Chelyabinsk coal basin (South Ural, Russia), was investigated using chemical microprobe analysis, in situ single-crystal X-ray diffraction analysis (27–727 °C), and Raman spectroscopy. 'Rhythmite' is orthorhombic, Pnma: a = 17.0749(6), b = 15.1029(5), c = 13.2907(4) Å, and V = 3427.42(18) Å3 (R1 = 0.045). The crystal structure of 'rhythmite' consists of a porous framework formed by Ca-O bonds and SiO4 tetrahedra with additional Ca2+ cations and Cl− anions in the structure interstices. The framework is built up from multinuclear [Ca15(SiO4)4]14+ fundamental building blocks (FBBs) cut from the crystal structure of α-Ca3SiO4Cl2 ('albovite'). The FBBs are linked by sharing common Ca atoms to form a network with an overall pcu topology. The empirical chemical formula was calculated as Ca29.02(Si7.89Al0.05P0.05)Ʃ7.99O32Cl26 (on the basis of Cl + O = 58). 'Rhythmite' is stable up to 627 °C and expands slightly anisotropically (αmax/αmin = 1.40) in the ab and bc planes and almost isotropically in the ac plane (α33/α11 = 1.02) with the following thermal expansion coefficients (×106 °C−1): α11 = 14.6(1), α22 = 20.5(4), α33 = 15.0(3), and αV = 50.1(6) (room temperature). During expansion, the silicate tetrahedra remain relatively rigid with average bond length changes of less than 0.5%. A structural complexity analysis indicates that 'rhythmite' is complex, with IG,total = 920.313 (bits/u.c.), which significantly exceeds the average value of structural complexity for silicates and is caused by the modular framework construction and the presence of a large number of independent positions in the crystal structure. [ABSTRACT FROM AUTHOR]

Nefedovite, Na5Ca4(PO4)4F, has been investigated by in situ high-temperature powder (30–690 °C) and single crystal (27–827 °C) X-ray diffraction and Raman spectroscopy. Nefedovite is tetragonal, space group I-4, a = 11.6560(2), c = 5.4062(2) Å, V = 734.50(2) Å3 (R1 = 0.0149). Nefedovite is a 1D antiperovskite, since its crystal structure contains chains of corner-sharing anion-centered [FCa4Na2]9+ octahedra. The chains are parallel to the c direction. Nefedovite is stable up to 727 °C and undergoes a displacive phase transition in the temperature range 277–327 °C. With increasing temperature, the PO4 tetrahedra in the crystal structure of nefedovite gradually rotate around the imaginary fourfold inversion axes aligning the O2…O3 edge parallel to [110], which ultimately leads to the appearance of the mirror plane perpendicular to the c direction and the change of space group from I-4 (82) to I4/m (87). The crystal structure of nefedovite expands strongly anisotropically with the direction of the maximum thermal expansion oriented perpendicular to the chains of anion-centered octahedra. The information-based structural complexity analysis demonstrates that both low- and high-temperature modifications of nefedovite are structurally simple with the IG,total value less than 100 bits per unit cell. The structural complexity decreases along the phase transition, which is typical for displacive phase transitions. [ABSTRACT FROM AUTHOR]

The information-entropy measures of the complexity of nets are proposed that take into consideration both the vertices and edges of nets. The parameters quantify the amount of Shannon information per element (vertex or edge) and per the translationally independent parts of the nets. The nets can be classified according to their complexity into very simple (0–20 bit per cell), simple (20–100 bit per cell), intermediate (100–500 bit per cell), complex (500–1000 bit per cell), and very complex (>1000 bit per cell). The information entropies for 1936 3D nets were calculated and analysed, showing that the simplest (information-poor) nets possess the lowest transitivities. The majority of the most common nets in metal–organic frameworks (MOFs) are the simplest nets within their respective categories (i.e. among the nets with the same coordination of vertices). Since the information is directly related to entropy, which is understood as a statistical parameter, the preference of the simplest nets in MOFs is at least in part governed by their low information contents and high configurational entropies. [ABSTRACT FROM AUTHOR]

Flexible crystal structures, which exhibit single-crystal-to-single-crystal (SCSC) transformations, are attracting attention in many applied aspects: magnetic switches, catalysis, ferroelectrics and sorption. Acid treatment for titanosilicate material AM-4 and natural compounds with the same structures led to SCSC transformation by loss Na+, Li+ and Zn2+ cations with large structural changes (20% of the unit-cell volume). The conservation of crystallinity through complex transformation is possible due to the formation of a strong hydrogen bonding system. The mechanism of transformation has been characterized using single-crystal X-ray diffraction analysis, powder diffraction, Rietvield refinement, Raman spectroscopy and electron microscopy. The low migration energy of cations in the considered materials is confirmed using bond-valence and density functional theory calculations, and the ion conductivity of the AM-4 family's materials has been experimentally verified. [ABSTRACT FROM AUTHOR]

Flotation reagents are significant for modifying the interfacial characteristics of mineral grains to achieve the effective separation of minerals. Since the 1960s, when quantum chemistry was first introduced into the study of flotation reagents, many achievements have been made, although some controversial topics remain. The application of quantum chemistry in the research of flotation reagents for the separation of various minerals in the past decade is herein comprehensively and systematically reviewed. The main directions and gaps of current research are pointed out, the theoretical basis for the design and development of novel flotation reagents is summarized, and more importantly, the potential for the targeting design and development of efficient, selective, and environmentally friendly flotation reagent molecules by means of quantum chemistry is explored. [ABSTRACT FROM AUTHOR]

In this study, galeite, Na15(SO4)5ClF4 and schairerite, Na21(SO4)7ClF6 were investigated via in situ single-crystal X-ray diffraction in the temperature range of 300–750 K. Galeite and schairerite are trigonal, P31m, a = 12.1903(2), c = 13.9454(2) Å, V = 1794.69(6) Å3, and Z = 3 (R1 = 0.0273, 300 K) for galeite and a = 12.1859(3), c = 19.3080(6) Å, V = 2483.04(14) Å3, and Z = 3 (R1 = 0.0334, 300 K) for schairerite. The crystal structures of galeite and schairerite are based upon frameworks consisting of alternating face- and corner-sharing fluorine- and chlorine-centered octahedra. Galeite and schairerite can be attributed to 5H (galeite) and 7H (schairerite) antiperovskite polytypes, respectively. It was observed that schairerite undergoes at least one reversible phase transition before it starts to lose its crystallinity at 750 K. This phase transition occurs in the temperature range of 550–600 K. The high-temperature modification of schairerite is trigonal, with the centrosymmetric space group P-3m1 and the unit-cell parameters a = 7.0714(2), c = 19.5972(7) Å, V = 848.66(6) Å3, and Z = 1. Galeite is stable up to 600 K. The crystal structures of minerals expand anisotropically, and, in both cases, the strongest thermal expansion was parallel to the modules of face-sharing anion-centered octahedra. The structural complexity analysis showed that galeite is complex (695.175 bits/cell) and that the LT-modification of schairerite is very complex (1064.990 bits/cell), whereas its HT-modification is intermediate in complexity (256.755 bits/cell). The complexities of LT- and HT-polymorphs of schairerite are consistent with the general observations regarding structures with positional disorder: complexity decreases with increasing temperature, and simpler polymorphs have lower physical density. [ABSTRACT FROM AUTHOR]

The crystal structure of Pb10(PO4)6O, the proposed matrix for the potential room-temperature superconductor LK-99, Pb10−xCux(PO4)6O (x = 0.9–1.0), has been reinvestigated via single-crystal X-ray diffraction using crystals prepared by Merker and Wondratschek (Z. Anorg. Allg. Chem. 1960, 306, 25–29). The crystal structure is trigonal, P 3 ¯ , a = 9.8109(6), c = 14.8403(12) Å, V = 1237.06(15), R1 = 0.0413 using 3456 unique observed reflections. The crystal structure of Pb10(PO4)6O is a superstructure with regard to the 'standard' P63/m apatite structure type. The doubling of the c parameter is induced through the ordering of the split sites of 'additional' O' atoms within the structure channels running parallel to the c axis and centered at (00z). The O' atoms form short bonds to the Pb1 atoms, resulting in splitting the Pb1 site into two, Pb1A and Pb1B. The structural distortions are further transmitted to the Pb phosphate framework formed by four Pb2 sites and PO4 groups. The structure data previously reported by Krivovichev and Burns (Z. Kristallogr. 2003, 218, 357–365) may either correspond to the Pb10(PO4)6Ox(OH)2−2x (x ~ 0.4) member of the Pb10(PO4)6O—Pb10(PO4)6(OH)2 solid solution series, or to the high-temperature polymorph of Pb10(PO4)6O (with the phase with doubled c parameter being the low-temperature polymorph). [ABSTRACT FROM AUTHOR]

The mineral-like anthropogenic phase Zn(NH3)2Cl2, with ammine (NH30) complexes from the burned dumps of the Chelyabinsk coal basin (South Urals, Russia), has been investigated using single-crystal and high-temperature powder X-ray diffraction, and Raman and infrared (IR) spectroscopy. The anthropogenic Zn(NH3)2Cl2 is orthorhombic, Imma, a = 7.7399(6), b = 8.0551(5), c = 8.4767(8) Å, V = 528.49(7) Å3, R1 = 0.0388 at −73 °C. Its crystal structure is based upon isolated ZnN2Cl2 tetrahedra connected by hydrogen bonds (between NH3 groups and Cl atoms) into a three-dimensional network. Upon heating, the Zn(NH3)2Cl2 phase is stable up to about 150 °C, which is in good agreement with the data on the temperature of its formation. The crystal structure of Zn(NH3)Cl2 expands anisotropically with the strongest thermal expansion observed along the a axis. The thermal expansion of the structure is controlled by the changes in the hydrogen bonding system. The Raman and IR spectroscopic characteristics of this phase are close to those of the mineral ammineite, CuCl2(NH3)2. The studied anthropogenic phase, formed in the unique conditions of burned coal dumps, is identical to the synthetic Zn(NH3)2Cl2. [ABSTRACT FROM AUTHOR]

The chemical and structural diversity of minerals containing sulfur as an essential mineral-forming element has been analyzed in terms of the concept of mineral systems and the information-based structural and chemical complexity parameters. The study employs data for 1118 sulfur mineral species approved by the International Mineralogical Association. All known sulfur minerals belong to nine mineral systems, with the number of essential components ranging from one to nine. The chemical and structural complexity of S minerals correlate with each other; that is, on average, chemical complexification results in structural complexification. The minerals with S–O bonds (sulfates and sulfites) are more complex than those without S–O bonds (sulfides and sulfosalts). However, the most complex sulfur mineral known so far is incomsartorite, Tl6Pb144As246S516, a sulfosalt. The complexity-generating mechanism in sulfides and sulfosalts is the complex combination of different modules excised from parent PbS or SnS archetypes with the subsequent formation of superstructures. The drivers for structural complexity in sulfates are more diverse and, in addition to modular construction and superstructures, also include a high hydration state, the presence of polyatomic clusters, and framework complexity. The most complex Martian minerals are most probably halotrichite-group minerals. The chemical and structural complexity increases with the passage of geological time with the formation of the most complex sulfosalts at Lengenbach (Swiss Alps) triggered by life (activity of sulfur-reducing bacteria). [ABSTRACT FROM AUTHOR]

Minerals are information-rich materials that offer researchers a glimpse into the evolution of planetary bodies. Thus, it is important to extract, analyze, and interpret this abundance of information to improve our understanding of the planetary bodies in our solar system and the role our planet's geosphere played in the origin and evolution of life. Over the past several decades, data-driven efforts in mineralogy have seen a gradual increase. The development and application of data science and analytics methods to mineralogy, while extremely promising, has also been somewhat ad hoc in nature. To systematize and synthesize the direction of these efforts, we introduce the concept of "Mineral Informatics," which is the next frontier for researchers working with mineral data. In this paper, we present our vision for Mineral Informatics and the X-Informatics underpinnings that led to its conception, as well as the needs, challenges, opportunities, and future directions of the field. The intention of this paper is not to create a new specific field or a sub-field as a separate silo, but to document the needs of researchers studying minerals in various contexts and fields of study, to demonstrate how the systemization and enhanced access to mineralogical data will increase cross- and interdisciplinary studies, and how data science and informatics methods are a key next step in integrative mineralogical studies. [ABSTRACT FROM AUTHOR]

The crystal structure of quintinite, Mg4Al2(OH)12(CO3)·3H2O, from the Jacupiranga alkaline complex (Cajati, São Paulo, Brazil), was refined for two samples (91002 and C7029) using single-crystal X-ray diffraction data. The mineral crystallizes in the P-3c1 space group, a = 5.246/5.298, c = 15.110/15.199 Å for samples 91002/C7029. The crystal structure consists of octahedral sheets with Mg and Al ordering according to a 3 × 3 superstructure. The Mg and Al atoms are coordinated by six hydroxylated oxygen atoms; the average and bond distances are in the ranges 2.022–2.053 Å and 1.974–1.978 Å, respectively. The interlayer structures are identical (in contradiction to the previous assumptions), and consist of disordered (CO3)2− groups and (H2O)0 molecules. The samples from Jacupiranga can be identified as quintinite-2T, which is the second finding of this polytype after the Kovdor alkaline complex (Kola peninsula, Russia). The powder X-ray diffraction pattern of quintinite-2T contains weak superstructure reflection at 4.57 Å (010), indicative of Mg and Al ordering. An important crystal-chemical criterion of quintinite is the interlayer distance (d00n-value) of ~7.56 Å, which is steady among natural specimens from various findings worldwide. [ABSTRACT FROM AUTHOR]

The crystal structure of manganotychite has been refined using the holotype specimen from the Alluaiv Mountain, Lovozero massif, Kola peninsula, Russia. The mineral is cubic, Fd 3 ¯ , a = 14.0015(3) Å, V = 2744.88(18) Å3, Z = 8, R1 = 0.020 for 388 independently observed reflections. Manganotychite is isotypic to tychite and ferrotychite. Its crystal structure is based upon a three-dimensional infinite framework formed by condensation of MnO6 octahedra and CO3 groups by sharing common O atoms. The sulfate groups and Na+ cations reside in the cavities of the octahedral-triangular metal-carbonate framework. In terms of symmetry and basic construction of the octahedral-triangular framework, the crystal structure of manganotychite is identical to that of northupite, Na3Mg(CO3)2Cl. The transition northupite → tychite can be described as a result of the multiatomic 2Cl− → (SO4)2− substitution, where both chlorine and sulfate ions are the extra-framework constituents. However, the positions occupied by sulfate groups and chlorine ions correspond to different octahedral cavities within the skeletons of Na atoms. The crystal structure of northupite can be considered as an interpenetration of two frameworks: anionic [Mg(CO3)2]2− octahedral-triangular framework and cationic [ClNa3]2− framework with the antipyrochlore topology. Both manganotychite and northupite structure types can be described as a modification of the crystal structure of diamond (or the dia net) via the following steps: (i) replacement of a vertex of the dia net by an M4 tetrahedron (no symmetry reduction); (ii) attachment of (CO3) triangles to the triangular faces of the M4 tetrahedra (accompanied by the Fd 3 ¯ m → Fd 3 ¯ symmetry reduction); (iii) filling voids of the resulting framework by Na+ cations (no symmetry reduction); and (iv) filling voids of the Na skeleton by either sulfate groups (in tychite-type structures) or chlorine atoms (in northupite). As a result, the information-based structural complexity of manganotychite and northupite exceeds that of the dia net. [ABSTRACT FROM AUTHOR]

The mineral-like phase Ca3SiO4Cl2, an anthropogenic anhydrous calcium chlorine-silicate from the Chelyabinsk coal basin has been investigated using single-crystal and high-temperature powder X-ray diffraction and Raman spectroscopy. The empirical formula of this phase was calculated as Ca2.96[(Si0.98P0.03)Σ1.01O4]Cl2, in good agreement with its ideal formula. Ca3SiO4Cl2 is monoclinic, space group P21/c, Z = 4, a = 9.8367(6) Å, b = 6.7159(4) Å, c = 10.8738(7) Å, β = 105.735(6)°, V = 691.43(8) Å3. The crystal structure is based upon the pseudo-layers formed by Ca–O and Si–O bonds separated by Cl atoms. The pseudo-layers are parallel to the (100) plane. The crystal structure of Ca3SiO4Cl2 was refined (R1 = 0.037) and stable up to 660 °C; it expands anisotropically with the direction of the strongest thermal expansion close to parallel to the [−101] direction, which can be explained by the combination of thermal expansion and shear deformations that involves the 'gliding' of the Ca silicate layers relative to each other. The Raman spectrum of the compound contains the following bands (cm–1): 950 (ν3), 848 (ν1), 600 (ν4), 466 (ν2), 372 (ν2). The bands near 100–200 cm−1 can be described as lattice modes. The compound had also been found under natural conditions in association with chlorellestadite. [ABSTRACT FROM AUTHOR]

Through the combination of low-temperature hydrothermal synthesis and room-temperature evaporation, a synthetic phase similar in composition and crystal structure to the Earth's most complex mineral, ewingite, was obtained. The crystal structures of both natural and synthetic compounds are based on supertetrahedral uranyl-carbonate nanoclusters that are arranged according to the cubic body-centered lattice principle. The structure and composition of the uranyl carbonate nanocluster were refined using the data on synthetic material. Although the stability of natural ewingite is higher (according to visual observation and experimental studies), the synthetic phase can be regarded as a primary and/or metastable reaction product which further re-crystallizes into a more stable form under environmental conditions. [ABSTRACT FROM AUTHOR]

Single crystals of Na2Cu+[Cu2+3O](AsO4)2Cl (1) and Cu3[Cu3O]2(PO4)4Cl2 (2) were prepared by chemical vapor transport reactions. Both crystal structures are based upon the same [O2Cu6]8+ chains formed by corner-sharing (OCu4)6+ tetrahedra and interconnected by (TO4)3− (T = P, As) tetrahedra into porous {[OCu3](TO4)2Cl}3− frameworks. The channels within the frameworks are occupied by Na+, Cu+ and Cl− ions in the crystal structure of 1, whereas the channels in the structure of 2 contain edge-sharing CuO4Cl tetragonal pyramids. Both compounds are structurally related to the previously described synthetic Na2Cu+[Cu2+3O](PO4)2Cl and NaCu2+[Cu2+3O](PO4)2Cl. The compound 2 is structurally and chemically related to yaroshevskite, Cu3[Cu3O]2(VO4)4Cl2, a mineral discovered in volcanic fumaroles, but the two structure types are drastically different. The crystal chemical analysis of the title and related compounds allows to recognize a family of at least four compounds based upon {[OCu3](TO4)2Cl}3− frameworks with channels occupied by different chemical constituents. [ABSTRACT FROM AUTHOR]

The crystal structure of sergeysmirnovite, MgZn2(PO4)2·4H2O (orthorhombic, Pnma, a = 10.6286(4), b = 18.3700(6), c = 5.02060(15) Å, V = 980.26(6) Å3, Z = 4), a new member of the hopeite group of minerals, was determined and refined to R1 = 0.030 using crystals from the Këster mineral deposit in Sakha-Yakutia, Russia. Similar to other members of the hopeite group, the crystal structure of sergeysmirnovite is based upon [Zn(PO4)]– layers interlinked via interstitial [MO2(H2O)4]2– octahedra, where M = Mg2+. The layers are parallel to the (010) plane. Within the layer, the ZnO4 tetrahedra share common corners to form chains running along [001]. Sergeysmirnovite is a dimorph of reaphookhillite, a mineral from the Reaphook Hill zinc deposit in South Australia. The relations between sergeysmirnovite and reaphookhillite are the same as those between hopeite and parahopeite. Topological and structural complexity analysis using information theory shows that the hopeite (sergeysmirnovite) structure type is more complex, both structurally and topologically, than the parahopeite (reaphookhillite) structure type. Such complexity relations contradict the general observation that more complex polymorphs possess higher physical density and higher stability, since parahopeite is denser than hopeite. It could be hypothesized that hopeite is metastable under ambient conditions and separated from parahopeite by a structural and topological reconstruction that requires an essential energy barrier that is difficult to overcome. [ABSTRACT FROM AUTHOR]

The production of electrolytic nickel includes the stage of leaching of captured firing nickel matte dust. The solutions formed during this process contain considerable amounts of Pb, which is difficult to extraction due to its low concentration upon the high-salt background. The sorption of lead from model solutions with various compositions by synthetic and natural titanosilicate sorbents (synthetic ivanyukite-Na-T (SIV), ivanyukite-Na-T, and AM-4) have been investigated. The maximal sorption capacity of Pb is up to 400 mg/g and was demonstrated by synthetic ivanyukite In solutions with the high content of Cl− (20 g/L), extraction was observed only with a high amount of Na (150 g/L). Molecular mechanisms and kinetics of lead incorporation into ivanyukite were studied by the combination of single-crystal and powder X-ray diffraction, microprobe analysis, and Raman spectroscopy. Incorporation of lead into natural ivanyukite-Na-T with the R3m symmetry by the substitution 2Na+ + 2O2− ↔ Pb2+ + □ + 2OH− leds to its transformation into the cubic P−43m Pb-exchanged form with the empirical formulae Pb1.26[Ti4O2.52(OH)1.48(SiO4)3]·3.32(H2O). [ABSTRACT FROM AUTHOR]

Topological analysis of the heteropolyhedral MT framework (where M and T are octahedral and tetrahedral cations, respectively) in the eudialyte‐type structure and its derivatives was performed based on a natural tiling analysis of the 3D cation. To analyze the migration paths of sodium cations in these structures, the Voronoi method was used. The parental eudialyte‐type MT framework is formed by isolated ZO6 octahedra, six‐membered [M(1)6O24] rings of edge‐sharing M(1)O6 octahedra, and two kinds of rings of tetrahedra, [Si3O9] and [Si9O27]. Different occupancies of M(2), M(3) and M(4) sites with variable coordination numbers by the additional Q, T* and M* cations, respectively, result in 12 different types of the MT framework. Based on the results of natural tilings calculations as well as theoretical analysis of migration paths, it is found that Na+ ions can migrate through six‐ and seven‐membered rings, while all other rings are too small for the migration. In eight types of MT frameworks, Na+‐ion migration and diffusion is possible at ambient temperature and pressure, while in four other types cages are connected by narrow windows and, as a result, the Na+ diffusion in them is complicated at ambient conditions because of the window diameter, but may be possible either at higher temperatures or under mild geological conditions for long periods of time. [ABSTRACT FROM AUTHOR]

Nine different samples of fluorellestadite from Chelyabinsk, Kizel and Kuznetsk coal basins were studied by single-crystal X-ray diffraction analysis, thermal X-ray diffraction (25–800 °C), Infrared (IR) and Raman spectroscopy. Fluorellestadite is hexagonal, space group P63/m, the unit-cell parameters for the nine samples studied vary within rather small ranges: a = 9.415(5) – 9.4808(7) Å, c = 6.906(2) – 6.938(8) Å, V = 530.3(4) – 538.41(9) Å3. The mineral is isotypic with apatite, the structure is based upon isolated TO4 tetrahedra, where the T position is statistically occupied by Si4+ and S6+ with the ideal ratio Si:S equal to 1:1. The fluorine atoms are located in channels of the Ca4[(S,Si)O4]6 framework oriented parallel to the c axis. The thermal expansion of fluorellestadite is almost isotropic in the temperature range 25–800 °C (for ambient temperature: αa = 12.0·10−6 °C−1, αc = 11.9·10−6 °C−1; for 800 °C: αa = 18.2·10−6 °C−1, αc = 18.6·10−6 °C−1). A similar thermal behavior had been observed for fluorapatite. Despite the same structure motifs and close conditions of formation, the samples of fluorellestadite show different S/Si/P occupancies for T site and the F/Cl/OH (X-position) ratios. [ABSTRACT FROM AUTHOR]

The new mineral vasilseverginite, ideally Cu9O4(AsO4)2(SO4)2, 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 tenorite, lammerite, stranskiite, lammerite-β, langbeinite, dolerophanite, sanidine, hematite, and gahnite. Vasilseverginite occurs as prismatic crystals up to 0.02 × 0.02 × 0.06 mm3 combined in groups or interrupted crusts up to 1 × 2 cm2 in area and up to 0.1 mm thick. It is transparent, bright green, with vitreous luster. Dcalc is 4.41 g⋅cm–3. Vasilseverginite is optically biaxial (–), α 1.816(5), β 1.870(5), γ 1.897(5), estimated 2V is 30(15)°. Chemical composition (wt%, electron-microprobe) is: CuO 64.03, ZnO 0.79, Fe2O3 0.25, P2O5 0.05, As2O5 20.83, SO3 14.92, total 100.87. The empirical formula calculated on O = 20 apfu is C u 8.78 Z n 0.11 F e 0.03 3 + Σ 8.92 A s 1.98 P 0.01 S 2.03 O 20 $\left(\mathrm{Cu}_{8.78} \mathrm{Zn}_{0.11} \mathrm{Fe}_{0.03}^{3+}\right)_{\Sigma 8.92} \mathrm{As}_{1.98} \mathrm{P}_{0.01} \mathrm{~S}_{2.03} \mathrm{O}_{20}$. Vasilseverginite is monoclinic, P21/n, a = 8.1131(4), b = 9.9182(4), c = 11.0225(5) Å, β = 110.855(2)°, V = 828.84(6) Å3, and Z = 2. The strongest reflections in the powder XRD pattern [d,Å(I)(hkl)] are: 7.13(41)(101̅), 5.99(70)(110, 111̅), 5.260(100)(101), 4.642(46)(111), 3.140(31)(031̅), 2.821(35)(023̅), 2.784(38)(132̅, 032̅), 2.597(35)(204̅), and 2.556(50) (231̅, 212). The crystal structure, solved using single-crystal X‑ray diffraction data, R1 = 0.025, is based upon complex [O4Cu9]10+ layers parallel to (101̅) that are composed of edge- and corner-sharing (OCu4) tetrahedra. The topology is unprecedented in inorganic structural chemistry. The crystal structure can be considered a hybrid of the structures of popovite Cu5O2(AsO4)2 and dolerophanite Cu2O(SO4) according to the scheme Cu9O4(AsO4)2(SO4)2 = Cu5O2(AsO4)2 + 2Cu2O(SO4). The chemical hybridization does not result in a significant increase in chemical complexity of vasilseverginite compared to the sum of those of popovite and dolerophanite, whereas the structural hybridization leads to the doubling of structural information per unit cell. The mineral is named in memory of the outstanding Russian mineralogist, geologist, and chemist Vasiliy Mikhailovich Severgin (1765–1826). [ABSTRACT FROM AUTHOR]

Crystallization of the M2+[(UO2)(T6+O4)2(H2O)](H2O)4 (M2+ = Ni, Mg, Zn, Co, Fe and Mn; T6+ = S, Se) compounds is characterized by the presence of three different structure types, which are built by similar uranyl-based sulfate/selenate chains linked into pseudolayers through H-bonding networks, but the stacking sequences are different and can be described by the 1M, 2O and 2M polytypic modifications. In order to establish the interplay between chemical composition and structural architecture, eleven new Ni-bearing uranyl sulfate–selenate compounds have been synthesized, as well as a new Zn-bearing uranyl sulfate. To provide the extensive comparison of all the compounds, the crystal structures of previously studied Co and Mn uranyl sulfates of this family of compounds were re-investigated, which allowed reconsideration of their unit-cell parameters and the space-group symmetries. It is shown that crystallization of particular polytypes is governed by the interplay of the ionic radii of M2+ and T6+ cations, while pH of the initial solutions affects the rate of crystallization. [ABSTRACT FROM AUTHOR]

The main goal of the paper is to contribute to the agenda of developing an algorithmic model for crystallization and measuring the complexity of crystals by constructing embeddings of 3D parallelohedra into a primitive cubic network (pcu net). It is proved that any parallelohedron P as well as tiling by P, except the rhombic dodecahedron, can be embedded into the 3D pcu net. It is proved that for the rhombic dodecahedron embedding into the 3D pcu net does not exist; however, embedding into the 4D pcu net exists. The question of how many ways the embedding of a parallelohedron can be constructed is answered. For each parallelohedron, the deterministic finite automaton is developed which models the growth of the crystalline structure with the same combinatorial type as the given parallelohedron. [ABSTRACT FROM AUTHOR]

Through the years, mineralogical studies have produced a tremendous amount of data on the atomic arrangement and mineral properties. Quite often, structural analysis has led to elucidate the role played by minor components, giving interesting insights into the physico-chemical conditions of mineral crystallization and allowing the description of unpredictable structures that represented a body of knowledge critical for assessing their technological potentialities. Using such a rich database, containing many basic acquisitions, further steps became appropriate and possible, into the directions of more advanced knowledge frontiers. Some of these frontiers assume the name of modularity, complexity, aperiodicity, and matter organization at not conventional levels, and will be discussed in this review. [ABSTRACT FROM AUTHOR]

Most research on polyoxometalates (POMs) has been devoted to synthetic compounds. However, recent mineralogical discoveries of POMs in mineral structures demonstrate their importance in geochemical systems. In total, 15 different types of POM nanoscale‐size clusters in minerals are described herein, which occur in 42 different mineral species. The topological diversity of POM clusters in minerals is rather restricted compared to the multitude of moieties reported for synthetic compounds, but the lists of synthetic and natural POMs do not overlap completely. The metal–oxo clusters in the crystal structures of the vanarsite‐group minerals ([As3+V4+2V5+10As5+6O51]7−), bouazzerite and whitecapsite ([M3+3Fe7(AsO4)9O8–;n(OH)n]), putnisite ([Cr3+8(OH)16(CO3)8]8−), and ewingite ([(UO2)24(CO3)30O4(OH)12(H2O)8]32−) contain metal–oxo clusters that have no close chemical or topological analogues in synthetic chemistry. The interesting feature of the POM cluster topologies in minerals is the presence of unusual coordination of metal atoms enforced by the topological restraints imposed upon the cluster geometry (the cubic coordination of Fe3+ and Ti4+ ions in arsmirandite and lehmannite, respectively, and the trigonal prismatic coordination of Fe3+ in bouazzerite and whitecapsite). Complexity analysis indicates that ewingite and morrisonite are the first and the second most structurally complex minerals known so far. The formation of nanoscale clusters can be viewed as one of the leading mechanisms of generating structural complexity in both minerals and synthetic inorganic crystalline compounds. The discovery of POM minerals is one of the specific landmarks of descriptive mineralogy and mineralogical crystallography of our time. [ABSTRACT FROM AUTHOR]

In the course of the investigation of the phase formation in a K-bearing uranyl sulfate system under low-temperature hydrothermal conditions, stepwise crystallization of eight chemically and structurally distinct uranyl-bearing phases, including six novel compounds, has been observed. The crystal structures of four new compounds are based on units with novel topologies, one of which has never been observed in uranyl sulfates and three others are unprecedented for the structural chemistry of inorganic oxysalts. The obtained phases were analyzed using single-crystal XRD, EDX, topological analysis and information-based structural complexity calculations. The analysis of the chemical evolution in the system shows that the amount of U and S in the crystalline phases increases and decreases, respectively, driven by the increase of the pH value. The solution was heated to 55 °C, which appears to be insufficient for the formation of zippeite-type K-bearing uranyl sulfates. The analysis of the behavior of structural complexity indicates that most complex compounds crystallize on the borders between stability fields of stable compounds with less complex structural architectures. [ABSTRACT FROM AUTHOR]

Behaviour of hingganite-(Y), Y2□Be2Si2O8(OH)2, on compression to 47 GPa has been studied by synchrotron-based in situ high-pressure single-crystal X-ray diffraction at room temperature in a diamond anvil cell. In the studied pressure range no obvious phase transitions have been observed. The compression of hingganite-(Y) crystal structure is anisotropic, with b axis showing the maximal compressibility. A fit of the experimental pressure–volume data by the Birch-Murnaghan third-order equation of state yielded the bulk modulus of 131(2) GPa and its pressure first derivative of 3.5(2). The difference between high-pressure behaviour of hingganite-(Y) and structurally related datolite is governed by the different chemical nature of interlayer cations. [ABSTRACT FROM AUTHOR]

Negevite, ideally NiP2, is a new phosphide mineral from pyrometamorphic complex of the Hatrurim Formation (the Mottled Zone), Southern Levant. It is found in phosphide assemblages of the Hatrurim Basin, south Negev Desert, Israel, and Daba-Siwaqa complex, Jordan. The mineral occurs as tiny isometric grains reaching 15 µm in size and forms intimate intergrowths with other phosphides related to the Fe-Ni-P system. In reflected light, negevite is white with yellowish tint and isotropic. Reflectance values for COM recommended wavelengths [R (%), λ (nm)] are as follows: 54.6 (470), 55.0 (546), 55.3 (589), 55.6 (650). Chemical composition of the holotype specimen (electron microprobe, wt%): Ni 42.57, Co 3.40, Fe 2.87, P 42.93, S 8.33, total 100.10, corresponding to the empirical formula (Ni0.88Co0.07Fe0.06)Σ1.01 (P1.68S0.31)Σ1.99. The crystal structure of negevite was solved and refined to R1 = 1.73% based on 52 independent observed [I >2σ(I)] reflections. The mineral is cubic, space group Pa3, a = 5.4816(5) Å, V = 164.71(3) ų, and Z = 4. Dx = 4.881(1) g/cm³ calculated on the basis of the empirical formula. Negevite is a first natural phosphide belonging to the pyrite structure type. It is a chemical and structural analog of vaesite, NiS2, krutovite, NiAs2, and penroseite, NiSe2. The well-explored catalytic and photocatalytic properties of a synthetic counterpart of negevite could provide new insights into the possible role of higher phosphides as a source of low-valent phosphorus in prebiotic phosphorylation processes. [ABSTRACT FROM AUTHOR]

This paper is a first detailed report of natural hexagonal solid solutions along the join Fe2P-Ni2P. Transjordanite, Ni2P, a Ni-dominant counterpart of barringerite (a low-pressure polymorph of Fe2P), is a new mineral. It was discovered in the pyrometamorphic phosphide assemblages of the Hatrurim Formation (the Dead Sea area, Southern Levant) and was named for the occurrence on the Transjordan Plateau, West Jordan. Later on, the mineral was confirmed in the Cambria meteorite (iron ungrouped, fine octahedrite), and it likely occurs in CM2 carbonaceous chondrites (Mighei group). Under reflected light, transjordanite is white with a beige tint. It is non-pleochroic and weakly anisotropic. Reflectance values for four COM recommended wavelengths are [Rmax/Rmin, % (λ, nm)]: 45.1/44.2 (470), 49.9/48.5 (546), 52.1/50.3 (589), 54.3/52.1 (650). Transjordanite is hexagonal, space group P62m; unit-cell parameters for the holotype specimen, (Ni1.72Fe0.27)1.99P1.02, are: a = 5.8897(3), c = 3.3547(2) Å, V = 100.78(1) ų, Z = 3. Dcalc = 7.30 g/cm³. The crystal structure of holotype transjordanite was solved and refined to R1 = 0.013 based on 190 independent observed [I > 2σ(I)] reflections. The crystal structure represents a framework composed of two types of infinite rods propagated along the c-axis: (1) edgesharing tetrahedra [M(1)P4] and (2) edge-sharing [M(2)P5] square pyramids. Determination of unit-cell parameters for 12 members of the Fe2P-Ni2P solid-solution series demonstrates that substitution of Ni for Fe in transjordanite and vice versa in barringerite does not obey Vegard's law, indicative of preferential incorporation of minor substituent into M(1) position. Terrestrial transjordanite may contain up to 3 wt% Mo, whereas meteoritic mineral bears up to 0.2 wt% S. [ABSTRACT FROM AUTHOR]

Experimental investigations of crystallization in a family of uranyl triacetate compounds with Na, K, Rb and Cs were performed. The crystal structures of two novel Cs- and Rb-bearing tri(acetato)uranylates were solved, and the content of H2O molecules in the crystal structure of K-bearing uranyl triacetate was refined. Synthesized compounds were analyzed using IR spectroscopy and single-crystal X-ray diffraction. Crystal chemical analysis of the M[(UO2)(CH3COO)3](H2O)n family (M = Na, K, Rb, Cs; n = 0–1.0) reveals the sequence of structural transformations depending on the size of alkali cation resulting in the symmetry reduction from cubic P 213 (for Na), through tetragonal I 41/a (for K and Rb) to triclinic P 1̅ space groups (for Cs), which is in accordance with the principle of morphotropism, suggested by Paul von Groth, founder of the Zeitschrift für Krystallographie journal, in 1870. [ABSTRACT FROM AUTHOR]

Manaevite-(Ce), a new vesuvianite-group mineral has been investigated by means of electron microprobe, TGA and DSC and CHN analysis of H2O, powder X-ray diffraction, single-crystal X-ray structure analysis, 139La NMR, 57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are a = 15.9247(13) Å, c = 11.9661(10) Å, space group P4/nnc. The structure model was solved and refined to R1 = 3.35% for 1757 independent observed reflections with I > 4σ(I). Manaevite-(Ce) is the first vesuvianite-group mineral with the species-defining role of REE3+ at the X3 site. The mineral contains two different kinds of hydroxyl anions. The first type of hydroxyl groups is associated with the O10 and O11 sites as observed for other vesuvianite-group members. Another type of OH groups is due to the hydrogarnet substitution (H4O4)4‒ ↔ (SiO4) 4‒ associated with the Z1 and Z2 sites. The incorporation of REE3+ into the crystal structure of manaevite-(Ce) proceeds via the substitution schemes 2Ca2+ ↔ Th4+ + □ and 3Ca2+ ↔ 2REE3+ + □, which results in the formation of vacancies at the X3 site and the presence of H2O molecules. [ABSTRACT FROM AUTHOR]

Single crystals of Rb2CaCu6(PO4)4O2 were synthesized by a hydrothermal method in the multicomponent system CuCl2–Ca(OH)2–RbCl–B2O3–Rb3PO4. The synthesis was carried out in the temperature range from 690 to 700 K and at the general pressure of 480–500 atm [1 atm = 101.325 kPa] from the mixture in the molar ratio 2CuO:CaO:Rb2O:B2O3:P2O5. The crystals studied by single‐crystal X‐ray analysis were found to be monoclinic, space group C2, a = 16.8913 (4), b = 5.6406 (1), c = 8.3591 (3) Å, β = 93.919 (3)°, V = 794.57 (4) Å3. The crystal structure of Rb2CaCu6(PO4)4O2 is similar to that of shchurovskyite and dmisokolovite and is based upon a heteropolyhedral open framework formed by polar layers of copper polyhedra linked via isolated PO4 tetrahedra. The presence of well‐isolated 2D heteropolyhedral layers in the title compound suggests low‐dimensional magnetic behavior which is masked, however, by the fierce competition between multiple ferromagnetic and antiferromagnetic exchange interactions. At TC = 25 K, Rb2CaCu6(PO4)4O2 reaches a magnetically ordered state with large residual magnetization. [ABSTRACT FROM AUTHOR]

The high‐temperature (HT) behaviour of lobanovite, K2Na(Fe2+4Mg2Na)Ti2(Si4O12)2O2(OH)4, was studied using in situ powder X‐ray diffraction in the temperature range 25–1000°C and ex situ single‐crystal X‐ray diffraction of 17 crystals quenched from different temperatures. HT iron oxidation associated with dehydroxylation starts at 450°C, similar to other ferrous‐hydroxy‐rich heterophyllosilicates such as astrophyllite and bafertisite. A prominent feature of lobanovite HT crystal chemistry is the redistribution of Fe and Mg+Mn cations over the M(2), M(3), M(4) sites of the octahedral (O) layer that accompanies iron oxidation and dehydroxylation. This HT redistribution of cations has not been observed in titanosilicates until now, and seems to be triggered by the need to maintain bond strengths at the apical oxygen atom of the TiO5 pyramid in the heteropolyhedral (H) layer during oxidation–dehydroxylation. Comparison of the HT behaviour of lobanovite with five‐coordinated Ti and astrophyllite with six‐coordinated Ti shows that the geometry of the Ti polyhedron plays a key role in the HT behaviour of heterophyllosilicates. The thermal expansion, geometrical changes and redistribution of site occupancies which occur in lobanovite under increasing temperature are reported. A brief discussion is given of minerals in which the cation ordering (usually for Fe and Mg) occurs together with iron oxidation–dehydroxylation at elevated temperatures: micas, amphiboles and tourmalines. Now this list is expanded by the inclusion of titanosilicate minerals. [ABSTRACT FROM AUTHOR]

Thermal behavior of three copper molybdates, lindgrenite, Cu3(MoO4)2(OH)2, szenicsite Cu3(MoO4)(OH)4, and cupromolybdite, Cu3O(MoO4)2, has been studied by high-temperature X-ray powder diffraction in the temperature range of 25–900 °C. The decomposition of lindgrenite and formation of cupromolybdite were observed at T > 325 °C according to the reaction: Cu3(MoO4)2(OH)2 → Cu3O(MoO4)2 + H2O. Szenicsite decomposes to cupromolybdite and tenorite at T > 350 °C according to the reaction: 2Cu3(MoO4)(OH)4 → Cu3O(MoO4)2 + 3CuO + 2H2↑. Cupromolybdite is stable up to 825 °C. The thermal expansion of lindgrenite, szenicsite and cupromolybdite is strongly anisotropic; the values of αmax/αmin are 5.6, 11.0 and 4.3, respectively. The maximal/minimal thermal expansion refers to the dominant direction of long/short Cu–O bonds owing to the distortion of CuO6 octahedral geometry due to the Jahn–Teller effect. For all three Cu molybdates, there are more or less aligned orientations of Jahn–Teller-distorted (CuO6) octahedra, which allows calculating the average 〈Cu–O〉 bond lengths along particular crystallographic directions. The 〈Cu–O〉 values observed are found to be in good correlation with the observed anisotropy of thermal expansion. The additional O2− anions in cupromolybdite act as coordination centers that form four strong Cu–O bonds each. These bonds propagate along the direction of the minimal thermal expansion, thus showing that the anion-centered structural motifs in cupromolybdite are the strongest after the Mo6+-centered (MoO4) tetrahedra. [ABSTRACT FROM AUTHOR]

Zuktamrurite, FeP2, is a new mineral, a natural iron diphosphide found in the pyrometamorphic rocks of the Hatrurim Formation, in the southern part of the Negev Desert, Israel and on the Transjordan Plateau, Jordan. The mineral occurs as irregular grains up to 50 µm in size associated with murashkoite, FeP, and barringerite, (Fe,Ni)2P. In reflected light, zuktamrurite is white with a distinct bluish tint. It is non-pleochroic but exhibits distinct anisotropy in bluish colours. Reflectance values for the IMA COM recommended wavelengths are [Rmax/Rmin, % (λ, nm)]: 50.40/47.20 (470); 49.16/46.23 (546); 48.97/46.16 (589); 49.40/46.40 (650). It is brittle. Electron microprobe analysis of the holotype specimen gave the following chemical composition (wt%, average of 5 points): Fe 40.23; Ni 7.97; P 51.70; total 99.90. The empirical formula calculated on the basis of 3 apfu is (Fe0.86Ni0.16)1.02P1.98 corresponding to FeP2. Zuktamrurite is orthorhombic, space group Pnnm, unit cell parameters refined from the single-crystal data: a 4.9276(6), b 5.6460(7), c 2.8174(4) Å, V 78.38(1) Å3, Z = 2. Dx = 5.003 g cm−3. The crystal structure was solved and refined to R1 = 0.0121 on the basis of 109 unique reflections with I > 2σ(I). The strongest lines of the powder X-ray diffraction pattern [(d, Å) (I, %) (hkl)]: 3.714 (54) (110); 2.820 (31) (020); 2.451 (100) (120, 101); 2.242 (55) (111); 1.760 (37) (211). The mineral is named for the Zuk-Tamrur cliff (Dead Sea) located nearby the type locality, the Halamish Wadi, southern Negev Desert, Israel. Zuktamrurite is the phosphide analogue of löllingite (loellingite), FeAs2. It is the most phosphorus-rich phosphide ever found in nature. [ABSTRACT FROM AUTHOR]