scholarly journals Dellagiustaite: A Novel Natural Spinel Containing V2+

Minerals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 4 ◽  
Author(s):  
Fernando Cámara ◽  
Luca Bindi ◽  
Adriana Pagano ◽  
Renato Pagano ◽  
Sarah Gain ◽  
...  
Keyword(s):  
Trivalent Cation ◽  
Chemical Formula ◽  
Inverse Spinel ◽  
Group Mineral ◽  
San Luis ◽  
Site Assignment ◽  
Mineral Assemblages ◽  
Ideal Stoichiometry ◽  
Tubular Inclusions ◽  
The Ideal

Dellagiustaite, ideally Al2V2+O4, is a new spinel-group mineral from Sierra de Comechingones, San Luis, Argentina, where it is found associated with hibonite (containing tubular inclusions, 5–100 μm, of metallic vanadium), grossite, and two other unknown phases with ideal stoichiometry of Ca2Al3O6F and Ca2Al2SiO7. A very similar rock containing dellagiustaite has been found at Mt Carmel (northern Israel), where super-reduced mineral assemblages have crystallized from high-T melts trapped in corundum aggregates (micro-xenoliths) within picritic-tholeiitic lavas ejected from Cretaceous volcanoes. In the holotype, euhedral grains of dellagiustaite are found as inclusions in grossite. The empirical average chemical formula of dellagiustaite is (Al1.09 V 0.91 2 + V 0.87 3 + Mg0.08 Ti 0.04 3 + Mn0.01)Σ3O4, but it may show limited replacement of V2+ by Mg and of V3+ by Al. As Al is the dominant trivalent cation, the ideal formula is Al2V2+O4 according to the current IMA rules. Dellagiustaite shows the usual space group of spinel-group minerals (Fd 3 ¯ m, R1 = 1.46%) with a = 8.1950(1) Å. The observed mean bond lengths <T–O> = 1.782(2) Å and <M–O> = 2.0445(9) Å, the observed site scattering (T = 13.3 eps, M = 22.5 eps), and the chemical composition show that dellagiustaite is an inverse spinel: T tetrahedra are occupied by Al3+, whereas M octahedra are occupied by V2+ and V3+, leading to the site assignment as TAlM( V 0.91 2 + V 0.88 3 + Al 0.09 3 + Mg0.08 Ti 0.03 3 + Mn0.01)O4.

scholarly journals Crystal Chemistry of Sulfates from the Apuan Alps (Tuscany, Italy). V. Scordariite, K8(Fe3+0.67□0.33)[Fe3+3O(SO4)6(H2O)3]2(H2O)11: A New Metavoltine-Related Mineral

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 702 ◽  
Author(s):  
Biagioni ◽  
Bindi ◽  
Mauro ◽  
Hålenius
Keyword(s):  
Crystal Structure ◽  
Layered Structure ◽  
New Mineral ◽  
Formula Unit ◽  
Crystal Data ◽  
Chemical Formula ◽  
X Ray ◽  
New Mineral Species ◽  
Apuan Alps ◽  
The Ideal

The new mineral species scordariite, K8(Fe3+0.67□0.33)[Fe3+3O(SO4)6(H2O)3]2(H2O)11, was discovered in the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. It occurs as pseudo-hexagonal tabular crystals, yellowish to brownish in color, up to 0.5 mm in size. Cleavage is perfect on {0001}. It is associated with giacovazzoite, krausite, gypsum, jarosite, alum-(K), and magnanelliite. Electron microprobe analyses give (wt %): SO3 47.31, Al2O3 0.66, Fe2O3 24.68, FeO 0.69, Na2O 0.52, K2O 17.36, H2Ocalc 15.06, total 106.28. The partitioning of Fe between Fe2+ and Fe3+ was based on Mössbauer spectroscopy. On the basis of 67 O atoms per formula unit, the empirical chemical formula is (K7.50Na0.34)Σ7.84(Fe3+6.29Al0.26Fe2+0.20)Σ6.75S12.02O50·17H2O. The ideal end-member formula can be written as K8(Fe3+0.67□0.33)[Fe3+3O(SO4)6(H2O)3]2(H2O)11. Scordariite is trigonal, space group R-3, with (hexagonal setting) a = 9.7583(12), c = 53.687(7) Å, V = 4427.4(12) Å3, Z = 3. The main diffraction lines of the observed X-ray powder pattern are [d(in Å), estimated visual intensity]: 8.3, strong; 6.6, medium; 3.777, medium; 3.299, medium; 3.189, medium; 2.884, strong. The crystal structure of scordariite has been refined using X-ray single-crystal data to a final R1 = 0.057 on the basis of 1980 reflections with Fo > 4σ(Fo) and 165 refined parameters. It can be described as a layered structure formed by three kinds of layers. As with other metavoltine-related minerals, scordariite is characterized by the occurrence of the [Fe3+3O(SO4)6(H2O)3]5− heteropolyhedral cluster.

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

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

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

Platinum-group mineral assemblages in the Platreef at the Sandsloot Mine, northern Bushveld Complex, South Africa

2006 ◽  
Vol 70 (1) ◽  
pp. 83-101 ◽  
Author(s):  
D. A. Holwell ◽  
I. McDonald ◽  
P. E. B. Armitage
Keyword(s):  
Small Volume ◽  
Bushveld Complex ◽  
Rock Type ◽  
Platinum Group Mineral ◽  
Main Zone ◽  
Group Mineral ◽  
Multi Stage ◽  
Mineral Assemblages ◽  
Base Metal Sulphides ◽  
Platinum Group

AbstractPlatinum group mineral (PGM) assemblages in the Platreef at Sandsloot, northern Bushveld Complex, in a variety of lithologies reveal a complex multi-stage mineralization history. During crystallization of the Platreef pyroxenites, platinum group elements (PGE) and base-metal sulphides (BMS) were distributed thoughout the interstitial liquid forming a telluride-dominant assemblage devoid of PGE sulphides. Redistribution of PGE into the metamorphic footwall by hydrothermal fluids has formed arsenide-, alloy- and antimonide-dominant assemblages, indicating a significant volatile influence during crystallization. Serpentinization of the footwall has produced an antimonide-dominant PGM assemblage. Parts of the igneous reef were subjected to alteration by a late-stage, Fe-rich fluid, producing ultramafic zones where the telluride-dominant assemblage has been recrystallized to an alloy-dominant one, particularly rich in Pt-Fe and Pd-Pb alloys. A thin, small-volume zone of PGE-BMS mineralization along the base of the hangingwall contains a primary PGM assemblage that is locally altered to one dominated by Pt/Pd germanides. This is thought to have formed when the new pulse of Main Zone magma entered the chamber, and scavenged PGE from the underlying Platreef pyroxenites. That each major rock type at Sandsloot contains a distinctive PGM assemblage reflects the importance of syn- and post-emplacement fluid and magmatic processes on the development of Platreef mineralization.

scholarly journals From structure topology to chemical composition. XXIII. Revision of the crystal structure and chemical formula of zvyaginite, Na2ZnTiNb2(Si2O7)2O2(OH)2(H2O)4, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia

2017 ◽  
Vol 81 (6) ◽  
pp. 1533-1550 ◽  
Author(s):  
E. Sokolova ◽  
A. Genovese ◽  
A. Falqui ◽  
F.C. Hawthorne ◽  
F. Cámara
Keyword(s):  
Crystal Structure ◽  
Kola Peninsula ◽  
Microprobe Analysis ◽  
Structural Formula ◽  
Chemical Formula ◽  
Titanium Silicate ◽  
Structure Topology ◽  
Diffraction Patterns ◽  
Alkaline Massif ◽  
The Ideal

AbstractThe crystal structure and chemical formula of zvyaginite, ideally Na2ZnTiNb2(Si2O7)2O2(OH)2(H2O)4, a lamprophyllite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia have been revised. The crystal structurewas refined with a new origin in space group C1, a = 10.769(2), b = 14.276(3), c = 12.101(2) Å, α = 105.45(3), β = 95.17(3), γ = 90.04(3)°, V = 1785.3(3.2) Å3, R1 = 9.23%. The electron-microprobe analysis gave the following empirical formula [calculated on 22 (O + F)]: (Na0.75Ca0.09K0.04□1.12)Σ2 (Na1.12Zn0.88Mn0.17Fe2+0.04□0.79)Σ3 (Nb1.68Ti1.25Al0.07)Σ3 (Si4.03O14)O2 [(OH)1.11F0.89]Σ2(H2O)4, Z = 4. Electron-diffraction patterns have prominent streaking along c* and HRTEM images show an intergrowth of crystalline zvyaginite with two distinct phases, both of which are partially amorphous. The crystal structure of zvyaginite is an array of TS (Titanium-Silicate) blocks connected via hydrogen bonds between H2O groups. The TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the [6]MO(1,4,5) sites are occupied mainly by Ti, Zn and Na and the [6]MO(2,3) sites are occupied by Na at less than 50%. In the H sheet, the [6]MH(1,2) sites are occupied mainly by Nb and the [8]AP(1) and [8]AP(2) sites are occupied mainly by Na and □. The MH and AP polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula is Na□Nb2NaZn□Ti(Si2O7)2O2(OH)2(H2O)4. Zvyaginite is a Zn-bearing and Na-poor analogue of epistolite, ideally (Na□)Nb2Na3Ti(Si2O7)2O2(OH)2(H2O)4. Epistolite and zvyaginite are related by the following substitution in the O sheet of the TS-block: (Naþ 2 )epi↔Zn2+ zvy +□zvy. The doubling of the t1 and t2 translations of zvyaginite relative to those of epistolite is due to the order of Zn and Na along a (t1) and b (t2) in the O sheet of zvyaginite.

Characteristics of ore minerals associated with gold at the Prestea mine, Ghana

1997 ◽  
Vol 61 (409) ◽  
pp. 879-894 ◽  
Author(s):  
Napoleon Q. Hammond ◽  
Hirokazu Tabata
Keyword(s):  
Gold Mineralization ◽  
Stoichiometric Composition ◽  
Oscillatory Zoning ◽  
Main Stage ◽  
Type I ◽  
Two Phase ◽  
Ore Minerals ◽  
Ideal Stoichiometry ◽  
Base Metal Sulphides ◽  
The Ideal

AbstractGold in Early Proterozoic Birimian greenstone at Prestea in Ghana is associated with base metal sulphides and sulphosalts including arsenopyrite, pyrite, sphalerite, chalcopyrite, pyrrhotite, galena, tetrahedrite, bournonite, boulangerite and jamesonite. The occurrence of the gold is intimately associated with arsenopyrite and the sulphosalts, and to a lesser extent with the other sulphides. The tetrahedrites at Prestea constitute the major component of sulphosalts associated with gold and occurring in two distinct types. Type I show ideal stoichiometric composition. Type II tetrahedrites deviated from the ideal stoichiometry and are represented approximately by the average formula (Cu,Ag)9.61(Fe,Zn)2.39(Sb,As)4S13. The tetrahedrites co-precipitated with gold exhibit ideal characteristics indicating an equilibruim state of the mineralizing fluid during precipitation. Three types of pyrites were distinguished by electron-microprobe analyses based on their As, Co and Ni composition. The As content in type I vary from 0.15 to 0.37 wt%, and contain up to 2 wt.% Co.Type II pyrites are As-rich and form the most dominant with As content ranging from 0.2 to 2.69 wt.%. Ni content varies from below-detection to 1000 ppm. Type III pyrites are poor in the trace elements and consistent with the stoichiometric composition. The mineralization occurred in three paragenetic stages from at least a two-phase hydrothermal fluid, with stage II forming a prolonged and main stage of the ore and gold mineralization. Redox changes in ore fluid which were triggered by episodic pressure releases during fissuring and fracturing caused fluctuation of the activity of the As/Ni ratio and subsequent oscillatory zoning of Ni in As-rich ores.

Platinum-group element mineralization in an As-rich magmatic sulphide system, Talnotry, southwest Scotland

2004 ◽  
Vol 68 (2) ◽  
pp. 395-411 ◽  
Author(s):  
M. R. Power ◽  
D. Pirrie ◽  
J. Jedwab ◽  
C. J. Stanley
Keyword(s):  
Solid Solution ◽  
Mineral Assemblage ◽  
Platinum Group Element ◽  
Group Element ◽  
Sulphide Mineralization ◽  
Group Mineral ◽  
Intermediate Solid Solution ◽  
Sulphide Liquid ◽  
Mineral Assemblages ◽  
Platinum Group

AbstractArsenic-rich magmatic sulphide mineralization is hosted by a diorite intrusion at Talnotry, southwest Scotland. A relatively abundant and diverse platinum-group mineral assemblage is present and is dominated by sperrylite, irarsite and electrum with subordinate merenskyite, michenerite and froodite. Early euhedral gersdorffite is enriched with respect to Rh, Ir and Pt and in some cases contains exsolved blebs of irarsite or euhedral grains of sperrylite. Sperrylite is also enclosed within silicates and sulphides indicating that it crystallized directly from an As-rich sulphide liquid. Pyrrhotite-chalcopyrite mineral assemblages are consistent with the fractional crystallization of monosulphide solid solution and are overlain by PGE-, Ni- and As-rich mineral assemblages indicative of crystallization from a NiAs liquid. Late-stage, cross-cutting, electrum-bearing chalcopyrite veins are consistent with the crystallization of Cu- and Au-rich intermediate solid solution. The chemistry, mineralogy and lithological relationships of the diorite suggest that it may be an appinite and as such is potentially analogous to the Au-rich lamprophyre dykes present within southwest Scotland.

Contrasting platinum-group mineral assemblages of the Kondyor massif (Russia): Implications for the sources of HSE in zoned-type ultramafic massifs

Lithos ◽  
2020 ◽  
Vol 376-377 ◽  
pp. 105800
Author(s):  
Kreshimir N. Malitch ◽  
Igor S. Puchtel ◽  
Elena A. Belousova ◽  
Inna Y. Badanina
Keyword(s):  
Platinum Group Mineral ◽  
Group Mineral ◽  
Mineral Assemblages ◽  
Platinum Group

Origin of Platinum-Group Mineral Assemblages from Placers in Rivers Draining from the Ural-Alaskan Type Itchayvayamsky Ultramafics, Far East Russia

2019 ◽  
Vol 57 (1) ◽  
pp. 91-104 ◽  
Author(s):  
Eugene G. Sidorov ◽  
Anton V. Kutyrev ◽  
Elena S. Zhitova ◽  
Valery M. Chubarov ◽  
Dmitry A. Khanin
Keyword(s):  
Far East ◽  
Platinum Group Mineral ◽  
Group Mineral ◽  
Mineral Assemblages ◽  
East Russia ◽  
Platinum Group

Superconducting Ba0.6K0.4BiO3: Thin film preparation by RF magnetron sputtering

1993 ◽  
Vol 8 (8) ◽  
pp. 1798-1804 ◽  
Author(s):  
C.J. Hou ◽  
H. Steinfink ◽  
L. Rabenberg ◽  
Claude Hilbert ◽  
Harry Kroger
Keyword(s):  
Thin Film ◽  
Magnetron Sputtering ◽  
Rf Magnetron Sputtering ◽  
Oxygen Annealing ◽  
Crystalline Films ◽  
Ideal Stoichiometry ◽  
Thin Film Preparation ◽  
High Transition ◽  
Film Preparation ◽  
The Ideal

Superconducting Ba0.6K0.4BiO3 thin films with transition temperatures up to 25 K have been successfully grown on SrTiO3 substrates using RF magnetron sputtering and postgrowth oxygen annealing. Systematic variation of the sputtering process parameters showed that optimum films can be grown on substrates heated to 400 °C in a 10 mTorr atmosphere containing 96% Ar and 4% O2 and using a target containing Ba, K, and Bi in ratios of 0.6:1.2:1.4. High transition temperature superconductivity was observed only in highly oriented, crystalline films having the ideal stoichiometry, Ba0.6K0.4BiO3.

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