Crystal Chemistry of Pyroaurite from the Kovdor Pluton, Kola Peninsula, Russia, and the Långban Fe–Mn deposit, Värmland, Sweden

Zhitova, Elena S.; Ivanyuk, Gregory Yu.; Krivovichev, Sergey V.; Yakovenchuk, Victor N.; Pakhomovsky, Yakov A.; Mikhailova, Yu. A.

doi:10.1134/s1075701517070121

Cited by 10 publications

(14 citation statements)

References 25 publications

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“…Thus, the presence of the reflection with d = 4.57 Å in the powder pattern of pure LDHs having M 2+ :M 3+ = 2:1 is a reliable indicator of cation ordering similar to the Li 2 Al LDHs [47][48][49][50]. In contrast to Cl-bearing hydrotalcite-supergroup members, the carbonate species have been structurally characterized in more details including recent single-crystal or Rietveld structure refinements of hydrotalcite [31], pyroaurite [51][52][53], quintinite [34,[53][54][55][56][57][58], takovite [59], and zaccagnaite [60]. It has been found that C atoms of CO 3 groups occupy central parts of the interlayer prisms (Figure 7b), whereas O atoms of CO 3 groups and H 2 O molecules are disordered around the middle points of the prism edges.…”

Section: Discussionmentioning

confidence: 99%

Crystal Chemistry of Chlormagaluminite, Mg4Al2(OH)12Cl2(H2O)2, a Natural Layered Double Hydroxide

et al. 2019

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Chlormagaluminite is the only Cl-dominated hydrotalcite-supergroup mineral species with M2+:M3+ = 2:1. The holotype sample of chlormagaluminite from the Kapaevskaya volcanic pipe (Irkutsk Oblast, Siberia, Russia) has been chemically and structurally characterized. The average chemical composition of the mineral is (electron microprobe, OH content is calculated by stoichiometry and H2O from the crystal-structure data, wt. %): MgO 33.85, FeO 1.09, Al2O3 22.07, Cl 14.72, H2Otot 30.96, Cl=O −3.39, total 99.30. The empirical formula based on Mg + Al + Fe = 6 atoms per formula unit (apfu) is [Mg3.91Fe2+0.07Al2.02(OH)12]Cl2.02(H2O)2.0(2). The crystal structure has been solved from single-crystal X-ray diffraction data in the space group P63/mcm, a = 5.268(3), c = 15.297(8) Å and V = 367.6(4) Å3. The refinement converged to R1 = 0.083 on the basis of 152 unique reﬂections with I > 2σ(I) collected at room conditions. The powder pattern contains standard reflections of a 2H polytype and two additional reflections [(010), d010 = 4.574 Å; (110), d110 = 2.647 Å] indicative of Mg and Al ordering according to the superstructure. The structure is based upon brucite-type octahedral layers with an ordered distribution of Mg and Al over octahedral sites. The Cl− anions and H2O molecules reside in the interlayer, providing a three-dimensional integrity of the structure.

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Section: Discussionmentioning

confidence: 99%

Crystal Chemistry of Chlormagaluminite, Mg4Al2(OH)12Cl2(H2O)2, a Natural Layered Double Hydroxide

et al. 2019

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“…The arrangement of Cl − anions and H 2 O groups in the interlayer space of dritsite shows statistical disorder ( Figure 5). The general architecture of the interlayer arrangement of dritsite is principally different from that of carbonate hydrotalcite supergroup minerals, namely quintinite, hydrotalcite, pyroaurite, stichtite, takovite, and zaccagnaite [38,[43][44][45][46][47][48][49][50], as shown in Figure 5c,d. In accordance with the approach by Bookin and Drits [23], the interlayer space can be considered as consisting of trigonal prisms formed by H atoms occupying the H1 site of the metal-hydroxide layers (Figure 5e,f).…”

Section: Crystal Structure Of Dritsite-2hmentioning

confidence: 99%

Dritsite, Li2Al4(OH)12Cl2·3H2O, a New Gibbsite-Based Hydrotalcite Supergroup Mineral

et al. 2019

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Dritsite, ideally Li2Al4(OH)12Cl2·3H2O, is a new hydrotalcite supergroup mineral formed as a result of diagenesis in the halite−carnallite rock of the Verkhnekamskoe salt deposit, Perm Krai, Russia. Dritsite forms single lamellar or tabular hexagonal crystals up to 0.25 mm across. The mineral is transparent and colourless, with perfect cleavage on {001}. The chemical composition of dritsite (wt. %; by combination of electron microprobe and ICP−MS; H2O calculated by structure refinement) is: Li2O 6.6, Al2O3 45.42, SiO2 0.11, Cl 14.33, SO3 0.21, H2Ocalc. 34.86, O = Cl − 3.24, total 98.29. The empirical formula based on Li + Al + Si = 6 apfu (atom per formula unit) is Li1.99Al4.00Si0.01[(OH)12.19Cl1.82(SO4)0.01]Σ14.02·2.60(H2O). The Raman spectroscopic data indicate the presence of O–H bonding in the mineral, whereas CO32– groups are absent. The crystal structure has been refined in the space group P63/mcm, a = 5.0960(3), c = 15.3578(13) Å, and V = 345.4(5) Å3, to R1 = 0.088 using single-crystal data. The strongest lines of the powder X-ray diffraction pattern (d, Å (I, %) (hkl)) are: 7.68 (100) (002), 4.422 (61) (010), 3.832 (99) (004, 012), 2.561 (30) (006), 2.283 (25) (113), and 1.445 (26) (032). Dritsite was found as 2H polytype, which is isotypic with synthetic material and shows strong similarity to chlormagalumite-2H. The mineral is named in honour of the Russian crystallographer and mineralogist Prof. Victor Anatol`evich Drits.

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“…(2012 b ). Quintinite-1 M was also described from rodingites at the Bazhenovskoe deposit (Middle Ural, Russia) (Krivovichev et al ., 2012 a ) and cavities of metasomatically altered gabbro at Mariinskoe deposit (Middle Ural, Russia) (Zhitova et al ., 2016 a ). We note that the structural model of the 1 M polytype proposed by us for quintinite-1 M was used by Jayanthi et al .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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Two 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 Pyroaurite from the Kovdor Pluton, Kola Peninsula, Russia, and the Långban Fe–Mn deposit, Värmland, Sweden

Cited by 10 publications

References 25 publications

Crystal Chemistry of Chlormagaluminite, Mg4Al2(OH)12Cl2(H2O)2, a Natural Layered Double Hydroxide

Crystal Chemistry of Chlormagaluminite, Mg4Al2(OH)12Cl2(H2O)2, a Natural Layered Double Hydroxide

Dritsite, Li2Al4(OH)12Cl2·3H2O, a New Gibbsite-Based Hydrotalcite Supergroup Mineral

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

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