Special Issue "New Mineral Species and Their Crystal Structures"

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Crystallography and Physical Chemistry of Minerals".

Deadline for manuscript submissions: closed (30 September 2018)

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Special Issue Editors

Guest Editor
Prof. Dr. Irina O. Galuskina

Department of Geochemistry, University of Silesia in Katowice, Katowice, Poland
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Interests: new minerals; crystal chemistry; pyrometamorphic rocks; skarns; rodingites; Raman spectroscopy; crystal growth
Guest Editor
Prof. Dr. Igor V. Pekov

Faculty of Geology, Lomonosov Moscow State University, Moscow, Russia
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Interests: : mineralogy; crystal chemistry; geochemistry of rare elements; alkaline rocks; volcanic exhalations; oxidation zone of ore deposits; new minerals; history of mineralogy

Special Issue Information

Dear Colleagues,

We have the pleasure to invite you to participate in a Special Issue of Minerals, devoted to new minerals and their crystal structures. In comparison with more than a million inorganic synthetic compounds, the number of currently-known mineral species slightly exceeds 5000. Each discovery of a new mineral, studied in detail and accompanied with rigorous descriptions, seem to be an important scientific event. New minerals widen our knowledge on the forms of concentrations of different chemical elements, including the rarest ones, in natural systems. Many of them demonstrate novel, sometimes very unusual structure types and intriguing properties. New mineral species attract attention as sensitive indicators of physical and chemical conditions of rock-forming processes in geology and as potential prototypes of new crystalline materials in modern technologies. And, surely, mineral diversity is one of most wonderful phenomena of nature.

Prof. Dr. Irina O. Galuskina
Prof. Dr. Igor V. Pekov
Guest Editors

Manuscript Submission Information

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Keywords

  • new mineral
  • crystal chemistry of minerals
  • crystal structure
  • new structure type
  • mineral group
  • mineral classification

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Open AccessEditorial Editorial for Special Issue “New Mineral Species and Their Crystal Structures”
Minerals 2019, 9(2), 106; https://doi.org/10.3390/min9020106
Received: 17 January 2019 / Revised: 30 January 2019 / Accepted: 1 February 2019 / Published: 13 February 2019
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Abstract
Mineralogy is the oldest and one of the most important sciences of the geological cycle [...] Full article

Research

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Open AccessArticle Verneite, Na2Ca3Al2F14, a New Aluminum Fluoride Mineral from Icelandic and Vesuvius Fumaroles
Minerals 2018, 8(12), 553; https://doi.org/10.3390/min8120553
Received: 26 October 2018 / Revised: 19 November 2018 / Accepted: 21 November 2018 / Published: 28 November 2018
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Abstract
Verneite, Na2Ca3Al2F14, is a new mineral first discovered in fumarolic samples from both Hekla, Iceland and Vesuvius, Italy. Additional occurrences are so far from Eldfell and Fimmvörduhals, both on Iceland. Verneite is cubic, I21 [...] Read more.
Verneite, Na2Ca3Al2F14, is a new mineral first discovered in fumarolic samples from both Hekla, Iceland and Vesuvius, Italy. Additional occurrences are so far from Eldfell and Fimmvörduhals, both on Iceland. Verneite is cubic, I213, a = 10.264(1) Å, V = 1081.4(3) Å3, Z = 4, and corresponds to the known synthetic compound. The empirical formula is Na2.01Ca2.82Al2.17F14.02 (scanning electron microscopy with energy dispersive spectrometer from an unpolished sample). It appears in crystals up to 20 μm in diameter, with {110}, {100}, and {111} as the main forms. In the crystal structure of its synthetic analogue, Na is coordinated by 7 F atoms in the form of a capped octahedron, Ca with 8 F atoms in the form of a bisdisphenoid, and Al with 6 F atoms in the form of an octahedron. The crystal structure of Na2Ca3Al2F14 contains sinuous chains of Ca coordination polyhedra interlacing with similarly sinuous chains of Na coordination polyhedra and forming together with them layers parallel to {100}. The intersecting layers parallel to three equivalent crystallographic planes form a three-dimensional mesh with Al coordinations imbedded in its holes. The characteristics of Ca coordinations in fluorides, as well as their relations to other ternary Na–Ca–Al fluorides are discussed. Verneite is named after Jules Verne. Full article
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Open AccessArticle Copper in Natural Oxide Spinels: The New Mineral Thermaerogenite CuAl2O4, Cuprospinel and Cu-Enriched Varieties of Other Spinel-Group Members from Fumaroles of the Tolbachik Volcano, Kamchatka, Russia
Minerals 2018, 8(11), 498; https://doi.org/10.3390/min8110498
Received: 11 October 2018 / Revised: 27 October 2018 / Accepted: 29 October 2018 / Published: 1 November 2018
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Abstract
This paper is the first description of natural copper-rich oxide spinels. They were found in deposits of oxidizing-type fumaroles related to the Tolbachik volcano, Kamchatka, Russia. This mineralization is represented by nine species with the following maximum contents of CuO (wt.%, given in [...] Read more.
This paper is the first description of natural copper-rich oxide spinels. They were found in deposits of oxidizing-type fumaroles related to the Tolbachik volcano, Kamchatka, Russia. This mineralization is represented by nine species with the following maximum contents of CuO (wt.%, given in parentheses): a new mineral thermaerogenite, ideally CuAl2O4 (26.9), cuprospinel, ideally CuFe3+2O4 (28.6), gahnite (21.4), magnesioferrite (14.7), spinel (10.9), magnesiochromite (9.0), franklinite (7.9), chromite (5.9), and zincochromite (4.8). Cuprospinel, formerly known only as a phase of anthropogenic origin, turned out to be the Cu-richest natural spinel-type oxide [sample with the composition (Cu0.831Zn0.100Mg0.043Ni0.022)Σ0.996(Fe3+1.725Al0.219Mn3+0.048Ti0.008)Σ2.000O4 from Tolbachik]. Aluminum and Fe3+-dominant spinels (thermaerogenite, gahnite, spinel, cuprospinel, franklinite, and magnesioferrite) were deposited directly from hot gas as volcanic sublimates. The most probable temperature interval of their crystallization is 600–800 °C. They are associated with each other and with tenorite, hematite, orthoclase, fluorophlogopite, langbeinite, calciolangbeinite, aphthitalite, anhydrite, fluoborite, sylvite, halite, pseudobrookite, urusovite, johillerite, ericlaxmanite, tilasite, etc. Cu-bearing spinels are among the latest minerals of this assemblage: they occur in cavities and overgrow even alkaline sulfates. Cu-enriched varieties of chrome-spinels (magnesiochromite, chromite, and zincochromite) were likely formed in the course of the metasomatic replacement of a magmatic chrome-spinel in micro-xenoliths of ultrabasic rock under the influence of volcanic gases. The new mineral thermaerogenite, ideally CuAl2O4, was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption. It forms octahedral crystals up to 0.02 mm typically combined in open-work clusters up to 1 mm across. Thermaerogenite is semitransparent to transparent, with a strong vitreous lustre. Its colour is brown, yellow-brown, red-brown, brown-yellow or brown-red. The mineral is brittle, with the conchoidal fracture, cleavage is none observed. D(calc.) is 4.87 g/cm3. The chemical composition of the holotype (wt.%, electron microprobe) is: CuO 25.01, ZnO 17.45, Al2O3 39.43, Cr2O3 0.27, Fe2O3 17.96, total 100.12 wt.%. The empirical formula calculated on the basis of 4 O apfu is: (Cu0.619Zn0.422)Σ1.041(Al1.523Fe3+0.443Cr0.007)Σ1.973O4. The mineral is cubic, Fd-3m, a = 8.093(9) Å, V = 530.1(10) Å3. Thermaerogenite forms a continuous isomorphous series with gahnite. The strongest lines of the powder X-ray diffraction pattern of thermaerogenite [d, Å (I, %) (hkl)] are: 2.873 (65) (220), 2.451 (100) (311), 2.033 (10) (400), 1.660 (16) (422), 1.565 (28) (511) and 1.438 (30) (440). Full article
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Open AccessArticle Parafiniukite, Ca2Mn3(PO4)3Cl, a New Member of the Apatite Supergroup from the Szklary Pegmatite, Lower Silesia, Poland: Description and Crystal Structure
Minerals 2018, 8(11), 485; https://doi.org/10.3390/min8110485
Received: 29 September 2018 / Revised: 18 October 2018 / Accepted: 22 October 2018 / Published: 26 October 2018
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Abstract
Parafiniukite, ideally Ca2Mn3(PO4)3Cl, is a new apatite-supergroup mineral from the Szklary pegmatite, Lower Silesia, Poland. It occurs as anhedral grains, up to 250 µm in size, dark olive green in colour, embedded in a mixture [...] Read more.
Parafiniukite, ideally Ca2Mn3(PO4)3Cl, is a new apatite-supergroup mineral from the Szklary pegmatite, Lower Silesia, Poland. It occurs as anhedral grains, up to 250 µm in size, dark olive green in colour, embedded in a mixture of Mn-oxides and smectites around beusite. It has a vitreous luster, and it is brittle with irregular, uneven fracture. The calculated density is 3.614 g·cm−3. Parafiniukite is hexagonal, space group P63/m, with unit-cell parameters a = 9.4900(6), c = 6.4777(5) Å, V = 505.22(5) Å3, Z = 2. The eight strongest reflections in the calculated X-ray powder diffraction pattern of parafiniukite are [d in Å (I) hkl]: 3.239 (39) 002; 2.801 (55) 211; 2.801 (76) 121; 2.740 (100) 300; 2.675 (50) 112; 2.544 (69) 202; 1.914 (31) 222; and 1.864 (22) 132. Chemical analysis by an electron microprobe gave (in wt%) P2O5 39.20, MgO 0.19, CaO 24.14, MnO 31.19, FeO 2.95, Na2O 0.05, F 0.39, Cl 3.13, H2O(calc) 0.68, O=(Cl,F) −0.87, sum 101.05. The resulting empirical formula on the basis of 13 anions per formula unit is (Mn2.39Ca2.34Fe0.22Mg0.03Na0.01)Σ4.99P3.00O12[Cl0.48(OH)0.41F0.11]. The crystal structure of parafiniukite was refined to an R1 = 0.0463 for 320 independent reflections with Fo > 4σ(Fo) and 41 refined parameters. Parafiniukite is isotypic with apatites. Manganese is the dominant cation at the M(2) site, and Ca is the dominant cation at the M(1) site. Full article
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Open AccessArticle Nöggerathite-(Ce), (Ce,Ca)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14, a New Zirconolite-Related Mineral from the Eifel Volcanic Region, Germany
Minerals 2018, 8(10), 449; https://doi.org/10.3390/min8100449
Received: 7 September 2018 / Revised: 2 October 2018 / Accepted: 3 October 2018 / Published: 12 October 2018
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Abstract
The new mineral nöggerathite-(Ce) was discovered in a sanidinite volcanic ejectum from the Laach Lake (Laacher See) paleovolcano in the Eifel region, Rhineland-Palatinate, Germany. Associated minerals are sanidine, dark mica, magnetite, baddeleyite, nosean, and a chevkinite-group mineral. Nöggerathite-(Ce) has a color that ranges [...] Read more.
The new mineral nöggerathite-(Ce) was discovered in a sanidinite volcanic ejectum from the Laach Lake (Laacher See) paleovolcano in the Eifel region, Rhineland-Palatinate, Germany. Associated minerals are sanidine, dark mica, magnetite, baddeleyite, nosean, and a chevkinite-group mineral. Nöggerathite-(Ce) has a color that ranges from brown to deep brownish red, with adamantine luster; the streak is brownish red. It occurs in cavities of sanidinite and forms long prismatic crystals measuring up to 0.02 × 0.03 × 1.0 mm, with twins and random intergrowths. Its density calculated using the empirical formula is 5.332 g/cm3. The Vickers hardness number (VHN) is 615 kgf/mm2, which corresponds to a Mohs’ hardness of 5½. The mean refractive index calculated using the Gladstone–Dale equation is 2.267. The Raman spectrum shows the absence of hydrogen-bearing groups. The chemical composition (electron microprobe holotype/cotype in wt %) is as follows: CaO 5.45/5.29, MnO 4.19/4.16, FeO 7.63/6.62, Al2O3 0.27/0.59, Y2O3 0.00/0.90, La2O3 3.17/3.64, Ce2O3 11.48/11.22, Pr2O3 1.04/0.92, Nd2O3 2.18/2.46, ThO2 2.32/1.98, TiO2 17.78/18.69, ZrO2 27.01/27.69, Nb2O5 17.04/15.77, total 99.59/99.82, respectively. The empirical formulae based on 14 O atoms per formula unit (apfu) are: (Ce0.59La0.165Nd0.11Pr0.05)Σ0.915Ca0.82Th0.07Mn0.50Fe0.90Al0.045Zr1.86Ti1.88Nb1.07O14 (holotype), and (Ce0.57La0.19Nd0.12Pr0.05Y0.06)Σ0.99Ca0.79Th0.06Mn0.49Fe0.77Al0.10Zr1.89Ti1.96Nb1.00O14 (cotype). The simplified formula is (Ce,Ca)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14. Nöggerathite-(Ce) is orthorhombic, of the space group Cmca. The unit cell parameters are: a = 7.2985(3), b = 14.1454(4), c = 10.1607(4) Å, and V = 1048.99(7) Å3. The crystal structure was solved using single-crystal X-ray diffraction data. Nöggerathite-(Ce) is an analogue of zirconolite-3O, ideally CaZrTi2O7, with Nb dominant over Ti in one of two octahedral sites and REE dominant over Ca in the eight-fold coordinated site. The strongest lines of the powder X-ray diffraction pattern (d, Å (I, %) (hkl)) are: 2.963 (91) (202), 2.903 (100) (042), 2.540 (39) (004), 1.823 (15) (400), 1.796 (51) (244), 1.543 (20) (442), and 1.519 (16) (282), respectively. The type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia (registration number 5123/1). Full article
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Open AccessArticle Cerromojonite, CuPbBiSe3, from El Dragόn (Bolivia): A New Member of the Bournonite Group
Minerals 2018, 8(10), 420; https://doi.org/10.3390/min8100420
Received: 25 July 2018 / Accepted: 30 August 2018 / Published: 21 September 2018
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Abstract
Cerromojonite, ideally CuPbBiSe3, represents a new selenide from the El Dragόn mine, Department of Potosí, Bolivia. It either occurs as minute grains (up to 30 µm in size) in interstices of hansblockite/quijarroite intergrowths, forming an angular network-like intersertal texture, or as [...] Read more.
Cerromojonite, ideally CuPbBiSe3, represents a new selenide from the El Dragόn mine, Department of Potosí, Bolivia. It either occurs as minute grains (up to 30 µm in size) in interstices of hansblockite/quijarroite intergrowths, forming an angular network-like intersertal texture, or as elongated, thin-tabular crystals (up to 200 μm long and 40 μm wide) within lath-shaped or acicular mineral aggregates (interpreted as pseudomorphs) up to 2 mm in length and 200 μm in width. It is non-fluorescent, black, and opaque, with a metallic luster and black streak. It is brittle, with an irregular fracture, and no obvious cleavage and parting. In plane-polarized incident light, cerromojonite is grey to cream-white, and weakly pleochroic, showing no internal reflections. Between crossed polarizers, cerromojonite is weakly anisotropic, with rotation tints in shades of brown and grey. Lamellar twinning on {110} is common. The reflectance values in air for the COM standard wavelengths (R1 and R2) are: 48.8 and 50.3 (470 nm), 48.2 and 51.8 (546 nm), 47.8 and 52.0 (589 nm), and 47.2 and 52.0 (650 nm). Electron-microprobe analyses yielded a mean composition of: Cu 7.91, Ag 2.35, Hg 7.42, Pb 16.39, Fe 0.04, Ni 0.02, Bi 32.61, Se 33.37, total 100.14 wt %. The empirical formula (based on 6 atoms pfu) is (Cu0.89Hg0.11)Σ = 1.00(Pb0.56Ag0.16Hg0.15 Bi0.11Fe0.01)Σ = 0.99Bi1.00Se3.01. The ideal formula is CuPbBiSe3. Cerromojonite is orthorhombic (space group Pn21m), with a = 8.202(1) Å, b = 8.741(1) Å, c = 8.029(1) Å, V = 575.7(1) Å3, Z = 4. Calculated density is 7.035 g·cm−3. The five strongest measured X-ray powder diffraction lines (d in Å (I/I0) (hkl)) are: 3.86 (25) (120), 2.783 (100) (122), 2.727 (55) (212), 2.608 (40) (310), and 1.999 (25) (004). Cerromojonite is a new member of the bournonite group, representing the Se-analogue of součekite, CuPbBi(S,Se)3. It is deposited from strongly oxidizing low-T hydrothermal fluids at a fSe2/fS2 ratio >1, both as primary and secondary phase. The new species has been approved by the IMA-CNMNC (2018-040) and is named for Cerro Mojon, the highest mountain peak closest to the El Dragón mine. Full article
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Open AccessArticle Aurihydrargyrumite, a Natural Au6Hg5 Phase from Japan
Minerals 2018, 8(9), 415; https://doi.org/10.3390/min8090415
Received: 28 August 2018 / Revised: 14 September 2018 / Accepted: 17 September 2018 / Published: 19 September 2018
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Abstract
Aurihydrargyrumite, a natural Au6Hg5 phase, was found in Iyoki, Uchiko, Ehime Prefecture, Shikoku Island, Japan. Aurihydrargyrumite with a metallic silver luster occurs as a submicron- to 2 μm-thick layer on the outermost surface of the placer gold. A prismatic face [...] Read more.
Aurihydrargyrumite, a natural Au6Hg5 phase, was found in Iyoki, Uchiko, Ehime Prefecture, Shikoku Island, Japan. Aurihydrargyrumite with a metallic silver luster occurs as a submicron- to 2 μm-thick layer on the outermost surface of the placer gold. A prismatic face may be formed by {001} and {100} or {110}. The streak is also silver white and its Mohs hardness value is ca. 2.5. Its tenacity is ductile and malleable, and its density, as calculated based on the empirical formula and powder unit-cell data, is 16.86 g·cm−3. The empirical formula of aurihydrargyrumite, on the basis of 11 Au + Hg, is Au5.95Hg5.05. Aurihydrargyrumite is hexagonal, P63/mcm, with the lattice parameters a = 6.9960(10) Å, c = 10.154(2) Å and V = 430.40(15) Å3, which is identical with the synthetic Au6Hg5 phase. The seven strongest lines in the powder X-ray diffraction (XRD) pattern [d in Å(I/I0)(hkl)] were 2.877(29)(112), 2.434(42)(113), 2.337(100)(104), 2.234(87)(211), 1.401(39)(314), 1.301(41)(404), and 1.225(65)(217). Aurihydrargyrumite forms through the weathering of mercury-bearing placer gold by involvement of self-electrorefining. This new mineral has been approved by the IMA-CNMNC (2017-003) and it is named for its composition, being a natural amalgam of gold (Latin: aurum) and mercury (Latin: hydrargyrum). Full article
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Open AccessArticle New Occurrence of Rusinovite, Ca10(Si2O7)3Cl2: Composition, Structure and Raman Data of Rusinovite from Shadil-Khokh Volcano, South Ossetia and Bellerberg Volcano, Germany
Minerals 2018, 8(9), 399; https://doi.org/10.3390/min8090399
Received: 28 August 2018 / Revised: 7 September 2018 / Accepted: 8 September 2018 / Published: 10 September 2018
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Abstract
Rusinovite, Ca10(Si2O7)3Cl2, was found at two new localities, including Shadil-Khokh volcano, South Ossetia and Bellerberg volcano, Caspar quarry, Germany. At both of these localities, rusinovite occurs in altered carbonate-silicate xenoliths embedded in volcanic [...] Read more.
Rusinovite, Ca10(Si2O7)3Cl2, was found at two new localities, including Shadil-Khokh volcano, South Ossetia and Bellerberg volcano, Caspar quarry, Germany. At both of these localities, rusinovite occurs in altered carbonate-silicate xenoliths embedded in volcanic rocks. The occurrence of this mineral is connected to specific zones of the xenolith characterized by a defined Ca:Si < 2 ratio. Chemical compositions, as well as the Raman spectra of the investigated rusinovite samples, correspond to the data from the locality of rusinovite holotype—Upper Chegem Caldera, Northern Caucasus, Russia. The most intense bands of the Raman spectra are related to vibrations of (Si2O7) groups. Unit cell parameters of rusinovite from South Ossetia are: a = 3.76330(4) Å, b = 16.9423(3) Å, c = 17.3325(2) Å, V = 1105.10(4) Å3, Z = 2. The performed synchrotron radiation diffraction experiments did not confirm a doubling of c as reported for the synthetic phase, Ca10(Si2O7)3Cl2. However, one-dimensional diffuse scattering parallel to b* has been observed. This can be interpreted with an ordered arrangement of Si2O7 groups creating layers with a doubled a parameter. Consequently, the two different displacements of neighbouring layers allow random stacking faults to occur. Full article
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Open AccessArticle Dynamic Disorder of Fe3+ Ions in the Crystal Structure of Natural Barioferrite
Minerals 2018, 8(8), 340; https://doi.org/10.3390/min8080340
Received: 13 July 2018 / Revised: 3 August 2018 / Accepted: 6 August 2018 / Published: 8 August 2018
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Abstract
A natural barioferrite, BaFe3+12O19, from a larnite–schorlomite–gehlenite vein of paralava within gehlenite hornfels of the Hatrurim Complex at Har Parsa, Negev Desert, Israel, was investigated by Raman spectroscopy, electron probe microanalysis, and single-crystal X-ray analyses acquired over the [...] Read more.
A natural barioferrite, BaFe3+12O19, from a larnite–schorlomite–gehlenite vein of paralava within gehlenite hornfels of the Hatrurim Complex at Har Parsa, Negev Desert, Israel, was investigated by Raman spectroscopy, electron probe microanalysis, and single-crystal X-ray analyses acquired over the temperature range of 100–400 K. The crystals are up to 0.3 mm × 0.1 mm in size and form intergrowths with hematite, magnesioferrite, khesinite, and harmunite. The empirical formula of the barioferrite investigated is as follows: (Ba0.85Ca0.12Sr0.03)∑1(Fe3+10.72Al0.46Ti4+0.41Mg0.15Cu2+0.09Ca0.08Zn0.04Mn2+0.03Si0.01)∑11.99O19. The strongest bands in the Raman spectrum are as follows: 712, 682, 617, 515, 406, and 328 cm−1. The structure of natural barioferrite (P63/mmc, a = 5.8901(2) Å, c = 23.1235(6) Å, V = 694.75(4) Å3, Z = 2) is identical with the structure of synthetic barium ferrite and can be described as an interstratification of two fundamental blocks: spinel-like S-modules with a cubic stacking sequence and R-modules that have hexagonal stacking. The displacement ellipsoids of the trigonal bipyramidal site show elongation along the [001] direction during heating. As a function of temperature, the mean apical Fe–O bond lengths increase, whereas the equatorial bond lengths decrease, which indicates dynamic disorder at the Fe2 site. Full article
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Open AccessArticle Kurchatovite and Clinokurchatovite, Ideally CaMgB2O5: An Example of Modular Polymorphism
Minerals 2018, 8(8), 332; https://doi.org/10.3390/min8080332
Received: 4 July 2018 / Revised: 25 July 2018 / Accepted: 26 July 2018 / Published: 2 August 2018
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Abstract
Kurchatovite and clinokurchatovite, both of ideal composition CaMgB2O5, from the type localities (Solongo, Buryatia, Russia, and Sayak-IV, Kazakhstan, respectively) have been studied using electron microprobe and single-crystal X-ray diffraction methods. The empirical formulae of the samples are Ca1.01 [...] Read more.
Kurchatovite and clinokurchatovite, both of ideal composition CaMgB2O5, from the type localities (Solongo, Buryatia, Russia, and Sayak-IV, Kazakhstan, respectively) have been studied using electron microprobe and single-crystal X-ray diffraction methods. The empirical formulae of the samples are Ca1.01Mg0.87Mn0.11Fe2+0.02B1.99O5 and Ca0.94Mg0.91Fe2+0.10Mn0.04B2.01O5 for kurchatovite and clinokurchatovite, respectively. The crystal structures of the two minerals are similar and based upon two-dimensional blocks arranged parallel to the c axis in kurchatovite and parallel to the a axis in clinokurchatovite. The blocks are built up from diborate B2O5 groups, and Ca2+ and Mg2+ cations in seven- and six-fold coordination, respectively. Detailed analysis of geometrical parameters of the adjacent blocks reveals that symmetrically different diborate groups have different degrees of conformation in terms of the δ angles between the planes of two BO3 triangles sharing a common O atom, featuring two discrete sets of the δ values of ca. 55° (B’ blocks) and 34° (B” blocks). The stacking of the blocks in clinokurchatovite can be presented as …(+B’)(+B”)(+B’)(+B”)… or [(+B’)(+B”)], whereas in kurchatovite it is more complex and corresponds to the sequence …(+B’)(+B”)(+B’)(−B’)(−B”)(−B’)(+B’)(+B”)(+B’)(−B’)(−B”)(−B’)… or [(+B’)(+B”)(+B’)(−B’)(−B”)(−B’)]. The B’:B” ratios for clinokurchatovite and kurchatovite are 1:1 and 2:1, respectively. According to this description, the two minerals cannot be considered as polytypes and their mutual relationship corresponds to the term modular polymorphs. From the viewpoint of information-based measures of structural complexity, clinokurchatovite (IG = 4.170 bits/atom and IG,total = 300.235 bits/cell) is structurally simpler than kurchatovite (IG = 4.755 bits/atom and IG,total = 1027.056 bits/cell). The high structural complexity of kurchatovite can be inferred from the modular character of its structure. The analysis of structural combinatorics in terms of the modular approach allows to construct the whole family of theoretically possible “kurchatovite”-type structures that bear the same structural features common for kurchatovite and clinokurchatovite. However, the crystal structures of the latter minerals are the simplest and are the only ones that have been observed in nature. The absence of other possible structures is remarkable and can be explained by either the maximum-entropy of the least-action fundamental principles. Full article
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Open AccessArticle Sharyginite, Ca3TiFe2O8, A New Mineral from the Bellerberg Volcano, Germany
Minerals 2018, 8(7), 308; https://doi.org/10.3390/min8070308
Received: 27 June 2018 / Revised: 17 July 2018 / Accepted: 17 July 2018 / Published: 21 July 2018
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Abstract
The new mineral sharyginite, Ca3TiFe2O8 (P21ma, Z = 2, a = 5.423(2) Å, b = 11.150(8) Å, c = 5.528(2) Å, V = 334.3(3) Å3), a member of the anion deficient [...] Read more.
The new mineral sharyginite, Ca3TiFe2O8 (P21ma, Z = 2, a = 5.423(2) Å, b = 11.150(8) Å, c = 5.528(2) Å, V = 334.3(3) Å3), a member of the anion deficient perovskite group, was discovered in metacarbonate xenoliths in alkali basalt from the Caspar quarry, Bellerberg volcano, Eifel, Germany. In the holotype specimen, sharyginite is widespread in the contact zone of xenolith with alkali basalt. Sharyginite is associated with fluorellestadite, cuspidine, brownmillerite, rondorfite, larnite and minerals of the chlormayenite-wadalite series. The mineral usually forms flat crystals up to 100 µm in length, which are formed by pinacoids {100}, {010} and {001}. Crystals are flattened on (010). Sharyginite is dark brown, opaque with a brown streak and has a sub-metallic lustre. In reflected light, it is light grey and exhibits rare yellowish-brown internal reflections. The calculated density of sharyginite is 3.943 g·cm-3. The empirical formula calculated on the basis of 8 O apfu is Ca3.00(Fe3+1.00Ti4+0.86Mn4+0.11Zr0.01Cr3+0.01Mg0.01)Σ2(Fe3+0.76Al0.20Si0.04)Σ1.00O8. The crystal structure of sharyginite, closely related to shulamitite Ca3TiFeAlO8 structure, consists of double layers of corner-sharing (Ti, Fe3+) O6 octahedra, which are separated by single layers of (Fe3+O4) tetrahedra. We suggest that sharyginite formed after perovskite at high-temperature conditions >1000°C. Full article
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Open AccessArticle Fiemmeite Cu2(C2O4)(OH)2∙2H2O, a New Mineral from Val di Fiemme, Trentino, Italy
Minerals 2018, 8(6), 248; https://doi.org/10.3390/min8060248
Received: 28 May 2018 / Revised: 7 June 2018 / Accepted: 11 June 2018 / Published: 12 June 2018
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Abstract
The new mineral species fiemmeite, Cu2(C2O4)(OH)22H2O, was found NE of the Passo di San Lugano, Val di Fiemme, Carano, Trento, Italy (latitude 46.312° N, longitude 11.406° E). It occurs in coalified woods [...] Read more.
The new mineral species fiemmeite, Cu2(C2O4)(OH)22H2O, was found NE of the Passo di San Lugano, Val di Fiemme, Carano, Trento, Italy (latitude 46.312° N, longitude 11.406° E). It occurs in coalified woods at the base of the Val Gardena Sandstone (upper Permian) which were permeated by mineralizing solutions containing Cu, U, As, Pb and Zn. The oxalate anions have originated from diagenesis of the plant remains included in sandstones. The mineral forms aggregate up to 1 mm across of sky blue platelets with single crystals reaching maximum dimensions of about 50 μm. Associated minerals are: baryte, olivenite, middlebackite, moolooite, brochantite, cuprite, devilline, malachite, azurite, zeunerite/metazeunerite, tennantite, chalcocite, galena. Fiemmeite is monoclinic, space group: P21/c with a = 3.4245(6), b = 10.141(2), c = 19.397(3) Å, β = 90.71(1)°, V = 673.6(2) Å3, Z = 4. The calculated density is 2.802 g/cm3 while the observed density is 2.78(1) g/cm3. The six strongest reflections in the X-ray powder diffraction pattern are: [dobs in Å (I)(hkl)] 5.079(100)(020), 3.072(58)(112), 9.71(55)(002), 4.501(50)(022), 7.02(28)(012), 2.686(25)(114). The crystal structure was refined from single-crystal data to a final R1 = 0.0386 for 1942 observed reflections [I > 2σ(I)] with all the hydrogen atoms located from a Difference–Fourier map. The asymmetric unit contains two independent Cu2+ cations that display a distorted square-bipyramidal (4+2) coordination, one oxalate anion, two hydroxyl anions and two water molecules. The coordination polyhedra of the two copper atoms share common edges to form polymeric rows running along [100] with composition [Cu2(C2O4)(OH)22H2O]n. These rows are held together by a well-established pattern of hydrogen bonds between the oxalate oxygens not involved in the coordination to copper, the hydrogen atoms of the water molecules and the hydroxyl anions. Full article
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Open AccessArticle Oyonite, Ag3Mn2Pb4Sb7As4S24, a New Member of the Lillianite Homologous Series from the Uchucchacua Base-Metal Deposit, Oyon District, Peru
Minerals 2018, 8(5), 192; https://doi.org/10.3390/min8050192
Received: 18 April 2018 / Revised: 25 April 2018 / Accepted: 1 May 2018 / Published: 2 May 2018
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Abstract
The new mineral species oyonite, ideally Ag3Mn2Pb4Sb7As4S24, has been discovered in the Uchucchacua base-metal deposit, Oyon district, Catajambo, Lima Department, Peru, as very rare black metallic subhedral to anhedral crystals, up [...] Read more.
The new mineral species oyonite, ideally Ag3Mn2Pb4Sb7As4S24, has been discovered in the Uchucchacua base-metal deposit, Oyon district, Catajambo, Lima Department, Peru, as very rare black metallic subhedral to anhedral crystals, up to 100 μm in length, associated with orpiment, tennantite/tetrahedrite, menchettiite, and other unnamed minerals of the system Pb-Ag-Sb-Mn-As-S, in calcite matrix. Its Vickers hardness (VHN100) is 137 kg/mm2 (range 132–147). In reflected light, oyonite is weakly to moderately bireflectant and weakly pleochroic from dark grey to a dark green. Internal reflections are absent. Reflectance values for the four COM wavelengths [Rmin, Rmax (%) (λ in nm)] are: 33.9, 40.2 (471.1); 32.5, 38.9 (548.3), 31.6, 38.0 (586.6); and 29.8, 36.5 (652.3). Electron microprobe analysis gave (in wt %, average of 5 spot analyses): Cu 0.76 (2), Ag 8.39 (10), Mn 3.02 (7), Pb 24.70 (25), As 9.54 (12), Sb 28.87 (21), S 24.30 (18), total 99.58 (23). Based on 20 cations per formula unit, the chemical formula of oyonite is Cu0.38Ag2.48Mn1.75Pb3.79Sb7.55As4.05S24.12. The main diffraction lines are (d in Å, hkl and relative intensity): 3.34 (−312; 40), 3.29 (−520; 100), 2.920 (−132; 40), 2.821 (−232; 70), 2.045 (004; 50). The crystal structure study revealed oyonite to be monoclinic, space group P21/n, with unit-cell parameters a = 19.1806 (18), b = 12.7755 (14), c = 8.1789 (10) Å, β = 90.471 (11)°, V = 2004.1 (4) Å3, Z = 2. The crystal structure was refined to a final R1 = 0.032 for 6272 independent reflections. Oyonite belongs to the Sb-rich members of the andorite homeotypic sub-series within the lillianite homologous series. The name oyonite is after the Oyon district, Lima Department, Peru, the district where the type locality (Uchucchacua mine) is located. Full article
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Open AccessArticle Tiberiobardiite, Cu9Al(SiO3OH)2(OH)12(H2O)6(SO4)1.5·10H2O, a New Mineral Related to Chalcophyllite from the Cretaio Cu Prospect, Massa Marittima, Grosseto (Tuscany, Italy): Occurrence and Crystal Structure
Minerals 2018, 8(4), 152; https://doi.org/10.3390/min8040152
Received: 23 March 2018 / Revised: 6 April 2018 / Accepted: 9 April 2018 / Published: 11 April 2018
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Abstract
The new mineral species tiberiobardiite, ideally Cu9Al(SiO3OH)2(OH)12(H2O)6(SO4)1.5·10H2O, has been discovered in the Cretaio Cu prospect, Massa Marittima, Grosseto, Tuscany, Italy, as very rare, light green, [...] Read more.
The new mineral species tiberiobardiite, ideally Cu9Al(SiO3OH)2(OH)12(H2O)6(SO4)1.5·10H2O, has been discovered in the Cretaio Cu prospect, Massa Marittima, Grosseto, Tuscany, Italy, as very rare, light green, vitreous, tabular {0001}, pseudo-hexagonal crystals, up to 200 μm in size and 5 μm in thickness, associated with brochantite. Electron microprobe analysis gave (in wt %, average of 5 spot analyses): SO3 10.37, P2O5 3.41, As2O5 0.05, SiO2 8.13, Al2O3 5.54, Fe2O3 0.74, CuO 62.05, and ZnO 0.03, for a total of 90.32. Based on an idealized O content of 42 atoms per formula unit, assuming the presence of 16 H2O groups and 13.5 cations (without H), the empirical formula of tiberiobardiite is (Cu8.69Al0.21Fe0.10)Σ9.00Al1.00(Si1.51P0.54)Σ2.05S1.44O12.53(OH)13.47·16H2O. The main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity)]: 9.4 (s), 4.67 (s), 2.576 (m), 2.330 (m), and 2.041 (mw). The crystal structure study revealed tiberiobardiite to be trigonal, space group R 3 ¯ , with unit-cell parameters a = 10.6860(4), c = 28.3239(10) Å, V = 2801.0(2) Å3, and Z = 3. The crystal structure was refined to a final R1 = 0.060 for 1747 reflections with Fo > 4σ (Fo) and 99 refined parameters. Tiberiobardiite is the Si-analogue of chalcophyllite, with Si4+ replacing As5+ through the coupled substitution As5+ + O2− = Si4+ + (OH). The name tiberiobardiite honors Tiberio Bardi (b. 1960) for his contribution to the study of the mineralogy of Tuscany. Full article
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Open AccessArticle New Mineral with Modular Structure Derived from Hatrurite from the Pyrometamorphic Rocks of the Hatrurim Complex: Ariegilatite, BaCa12(SiO4)4(PO4)2F2O, from Negev Desert, Israel
Minerals 2018, 8(3), 109; https://doi.org/10.3390/min8030109
Received: 19 February 2018 / Revised: 5 March 2018 / Accepted: 5 March 2018 / Published: 8 March 2018
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Abstract
Ariegilatite, BaCa12(SiO4)4(PO4)2F2O (R3¯m, a = 7.1551(6) Å, c = 41.303(3) Å, V = 1831.2(3) Å3, Z = 3), is a new member of the [...] Read more.
Ariegilatite, BaCa12(SiO4)4(PO4)2F2O (R 3 ¯ m, a = 7.1551(6) Å, c = 41.303(3) Å, V = 1831.2(3) Å3, Z = 3), is a new member of the nabimusaite group exhibiting a modular intercalated antiperovskite structure derived from hatrurite. It was found in a few outcrops of pyrometamorphic rocks of the Hatrurim Complex located in the territories of Israel, Palestine and Jordan. The holotype specimen is an altered spurrite marble from the Negev Desert near Arad city, Israel. Ariegilatite is associated with spurrite, calcite, brownmillerite, shulamitite, CO3-bearing fluorapatite, fluormayenite-fluorkyuygenite and a potentially new mineral, Ba2Ca18(SiO4)6(PO4)3(CO3)F3O. Ariegilatite is overgrown and partially replaced by stracherite, BaCa6(SiO4)2[(PO4)(CO3)]F. The mineral forms flat disc-shaped crystals up to 0.5 mm in size. It is colorless, transparent, with white steaks and vitreous luster. Optically, ariegilatite is uniaxial, negative: ω = 1.650(2), ε = 1.647(2) (λ = 589 nm). The mean composition of the holotype ariegilatite, (Ba0.98K0.01Na0.01)Σ1(Ca11.77Na0.08Fe2+0.06Mn2+0.05Mg0.04)Σ12(Si3.95Al0.03Ti0.02)Σ4(P1.70C0.16Si0.10S6+0.03V0.01)Σ2F2.04O0.96, is close to the end-member formula. The structure of ariegilatite is described as a stacking of the two modules {F2OCa12(SiO4)4}4+ and {Ba(PO4)2}4− along (001). Ariegilatite, as well as associated stracherite, are high-temperature alteration products of minerals of an early clinker-like association. These alterations took place under the influence of pyrometamorphism by-products, such as gases and fluids generated by closely-spaced combustion foci. Full article
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