THE FIRST BOTALLACKITE OCCURRENCE IN POLAND (POLKOWICE-SIEROSZOWICE MINE)

2017 ◽  
pp. 0-0 ◽  
Author(s):  
Rafał Siuda ◽  
Marek Łodziński ◽  
Marcin Syczewski ◽  
Łukasz Kruszewski ◽  
Jaroslav Pršek ◽  
...  
Keyword(s):  
Mine Water ◽  
Empirical Formula ◽  
Divalent Cations ◽  
Unit Cell ◽  
High Concentration ◽  
Unit Cell Parameters ◽  
Copper Mine ◽  
Cell Parameters ◽  
First Occurrence ◽  
Stable Polymorph

The presence of botallackite was recognized in an underground galery in the Polkowice-Sieroszowice copper mine. This mineral coexists with paratacamite, clinoatacamite, gypsum and halite. Botallackite crystallized from chloride-reach (3500 mg/dm3), warm (33°C) mine water. On the basis of microprobe analyzes, two types of botallackite were recognized. The first one contains only small amounts of Pb, Fe and Zn. These elements substitute Cu2+ ions in small proportions. Empirical formula of this botallackite is: (Cu1.94Pb0.02Fe0.02Zn0.02)S = 2.00Cl0.98(OH)3.02. The second type of the mineral were characterized by increased amounts of Pb, Fe, Zn. The empiric formula of this type of botallackite can be expressed as: (Cu1.85Pb0.09Fe0.04Zn0.02)S = 2.00Cl1.05(OH)2.95. The calculated unit-cell parameters of botallackite from Polkowice-Sieroszowice mine are as follows: a = 5.7165(2), b = 6.1362(2), c = 5.6325(2), b = 92.943(3). Botallackite is a least stable polymorph of Cu2Cl(OH)3 and finally transforms to more stable polymorphs. The botallackite recrystallization can be inhibit by high concentration of Ca2+ in the mine water. Substitution of Cu2+ ions by other divalent cations can slows the rapidity of recrystalization this mineral and prevent its further transformation also. The Polkowice-Sieroszowice mine is the first occurrence of botallackite in Poland.

Pb-Sb zrudnění z Antimonitové žíly, důl Rudolf, Bohutín (Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 275-280
Author(s):  
Pavel Škácha ◽  
Jiří Sejkora
Keyword(s):  
Czech Republic ◽  
Chemical Composition ◽  
Empirical Formula ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Ore District ◽  
Archive Material

The Pb-Sb mineralization with dominant stibnite and plagionite and associated semseyite and zinkenite was found in an archive material collected at the Antimonitová vein, Bohutín, Březové Hory ore district (Czech Republic). Plagionite forms subhedral aggregates up to 1 mm in size. The unit-cell parameters of plagionite for monoclinic space group C2/c refined from the X-ray powder data are: a 13.4890(17), b 11.8670(14), c 19.997(2) Å, β 107.199(8)° and V 3057.9(6) Å3. Its chemical composition (average of 26 analyses, based on 30 apfu) corresponds to the empirical formula Pb5.02Sb8.15S16.82. Associated zinkenite is forming subhedral crystals up to 1 mm in size. Its empirical formula can be expressed as (Cu0.25Ag0.02Fe0.01)Σ0.28Pb9.22Sb22.19S41.31 (average of 26 analyses, based on 73 apfu). Semseyite aggregates have the empirical formula (Pb8.72Fe0.14)8.86Sb8.42S20.73 (average of 11 analyses, based on 38 apfu).

Zeolitová mineralizace s gmelinitem-K z Jedlky u Benešova nad Ploučnicí (Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 213-229
Author(s):  
Petr Pauliš ◽  
Libor Hrůzek ◽  
Oldřich Janeček ◽  
Zdeněk Dolníček ◽  
Volker Betz ◽  
...  
Keyword(s):  
Czech Republic ◽  
Empirical Formula ◽  
Unit Cell ◽  
Mineral Species ◽  
Chemical Analyses ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Quantitative Chemical

A new locality of zeolite minerals occurs on the NE edge of the Jedlka village, at the SE slope of the Hlídka hill, 2 km to W of Benešov nad Ploučnicí (northern Bohemia, Czech Republic). The mineralization is developed in Cenozoic analcime-nepheline tephrite. Ten zeolite mineral species (gmelinite-K, analcime, harmotome, chabazite-Ca, lévyne-Ca, mezolite, natrolite, offretite, phillipsite-K, thomsonite-Ca) were found in small amygdule cavities of tephrite. The most interesting is gmelinite-K, a rare zeolite worldwide, which forms clear, white or slightly yellowish, hexagonal lenticular crystals up to 7 mm, always intergrown with the chabazite-Ca. The unit-cell parameters of gmelinite-K, refined from the powder X-ray data, are a = 13.795 (19), c = 9.811(6) Å and V = 1616.8(3) Å3; its quantitative chemical analyses correspond to the empirical formula (K2.32Ca1.86Sr0.53Na0.20Ba0.19)Σ5.10(Al8.14Si16.01O48)·22H2O.

Waimirite-(Y), orthorhombic YF3, a new mineral from the Pitinga mine, Presidente Figueiredo, Amazonas, Brazil and from Jabal Tawlah, Saudi Arabia: description and crystal structure

2015 ◽  
Vol 79 (3) ◽  
pp. 767-780 ◽  
Author(s):  
Daniel Atencio ◽  
Artur C. Bastos Neto ◽  
Vitor P. Pereira ◽  
José T. M. M. Ferron ◽  
M. Hoshino ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Saudi Arabia ◽  
Single Crystal ◽  
Electron Microprobe ◽  
Empirical Formula ◽  
Unit Cell ◽  
New Mineral ◽  
Charge Balance ◽  
Unit Cell Parameters ◽  
Cell Parameters

AbstractWaimirite-(Y) (IMA 2013-108), orthorhombic YF3, occurs associated with halloysite, in hydrothermal veins (up to 30 mm thick) cross-cutting the albite-enriched facies of the A-type Madeira granite (∼1820 Ma), at the Pitinga mine, Presidente Figueiredo Co., Amazonas State, Brazil. Minerals in the granite are 'K-feldspar', albite, quartz, riebeckite, 'biotite', muscovite, cryolite, zircon, polylithionite, cassiterite, pyrochlore-group minerals, 'columbite', thorite, native lead, hematite, galena, fluorite, xenotime-(Y), gagarinite-(Y), fluocerite-(Ce), genthelvite–helvite, topaz, 'illite', kaolinite and 'chlorite'. The mineral occurs as massive aggregates of platy crystals up to ∼1 μm in size. Forms are not determined, but synthetic YF3 displays pinacoids, prisms and bipyramids. Colour: pale pink. Streak: white. Lustre: non-metallic. Transparent to translucent. Density (calc.) = 5.586 g/cm3 using the empirical formula. Waimirite-(Y) is biaxial, mean n = 1.54–1.56. The chemical composition is (average of 24 wavelength dispersive spectroscopy mode electron microprobe analyses, O calculated for charge balance): F 29.27, Ca 0.83, Y 37.25, La 0.19, Ce 0.30, Pr 0.15, Nd 0.65, Sm 0.74, Gd 1.86, Tb 0.78, Dy 8.06, Ho 1.85, Er 6.38, Tm 1.00, Yb 5.52, Lu 0.65, O (2.05), total (97.53) wt.%. The empirical formula (based on 1 cation) is (Y0.69Dy0.08Er0.06Yb0.05Ca0.03Gd0.02Ho0.02Nd0.01Sm0.01Tb0.01Tm0.01Lu0.01)Σ1.00[F2.54〈0.25O0.21]Σ3.00. Orthorhombic, Pnma, a = 6.386(1), b = 6.877(1), c = 4.401(1) Å, V = 193.28(7) Å3, Z = 4 (powder data). Powder X-ray diffraction (XRD) data [d in Å (I) (hkl)]: 3.707 (26) (011), 3.623 (78) (101), 3.438 (99) (020), 3.205 (100) (111), 2.894 (59) (210), 1.937 (33) (131), 1.916 (24) (301), 1.862 (27) (230). The name is for the Waimiri-Atroari Indian people of Roraima and Amazonas. A second occurrence of waimirite-(Y) is described from the hydrothermally altered quartz-rich microgranite at Jabal Tawlah, Saudi Arabia. Electron microprobe analyses gave the empirical formula (Y0.79Dy0.08Er0.05Gd0.03Ho0.02Tb0.01Tm0.01Yb0.01)Σ1.00[F2.85O0.08〈0.07]Σ3.00. The crystal structure was determined with a single crystal from Saudi Arabia. Unit-cell parameters refined from single-crystal XRD data are a = 6.38270(12), b = 6.86727(12), c = 4.39168(8) Å, V = 192.495(6) Å3, Z = 4. The refinement converged to R1 = 0.0173 and wR2 = 0.0388 for 193 independent reflections. Waimirite-(Y) is isomorphous with synthetic SmF3, HoF3 and YbF3. The Y atom forms a 9-coordinated YF9 tricapped trigonal prism in the crystal structure. The substitution of Y for Dy, as well as for other lanthanoids, causes no notable deviations in the crystallographic values, such as unit-cell parameters and interatomic distances, from those of pure YF3.

scholarly journals Zeolitová mineralizace z Libé u Chebu (Česká republika)

2020 ◽  
Vol 28 (1) ◽  
pp. 152-160
Author(s):  
Petr Pauliš ◽  
Jiří Svejkovský ◽  
Zdeněk Dolníček ◽  
Petr Matys ◽  
Luboš Vrtiška ◽  
...  
Keyword(s):  
Czech Republic ◽  
Empirical Formula ◽  
Unit Cell ◽  
Chemical Analyses ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Snow White

A new occurrence of zeolite mineralization with phillipsite-K, phillipsite-Ca, thomsonite-Ca, natrolite and gonnardite has been discovered in an active basalt quarry in the Libá village near Cheb (Czech Republic). Phillipsites in small cavities form druses of white or colourless crystals up to 1 mm in size. Chemical analyses of phillipsite-K correspond to the empirical formula (K1.85Na1.24Ca0.83Ba0.27Sr0.01)Σ4.20(Al6.28Si10.33O32)·12H2O and phillipsite-Ca to (Ca1.84K1.33Na0.14Ba0.06)Σ3.37(Al5.97Si10.20O32)·12H2O. The unit-cell parameters were refined from the powder X-ray data for phillipsite-Ca as: a 9.924(2), b 14.309(3), c 8.7414(14) Å, β 124.92(2)° and V 1017.8(5) Å3. Thomsonite-Ca forms transparent hemispheric radial aggregates up to 1 cm in size. Its unit-cell parameters refined from the powder X-ray data are a 13.105(5), b 13.857(5), c 13.247(6) Å and V 2266.7(6) Å3 and its chemical analyses correspond to the empirical formula Ca1.79Sr0.18Na1.05(Al4.81 Si5.15)O20·6H2O. Natrolite occurs as snow white hemispheric radial clusters. Its unit-cell parameters refined from the powder X-ray data are a 18.326(7), b 18.569(7), c 6.594(3) Å and V 2243.8(9) Å3 and empirical formula is Na1.60Ca0.05(Al2.08 Si3.02)O10·2H2O. Gonnardite forms colourless or white aggregates of flat acicular crystals up to 2 mm in size. Its unit-cell parameters refined from the powder X-ray data are a 13.221(8), c 6.6233(4) Å and V 1156.9 Å3 and empirical formula is (Na3.14Ca2.21Sr0.02)Σ5.37(Al8.92Si11.41)Σ20.33O40·12H2O.

scholarly journals Manganiakasakaite-(La) and Ferriakasakaite-(Ce), Two New Epidote Supergroup Minerals from Piedmont, Italy

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 353
Author(s):  
Cristian Biagioni ◽  
Paola Bonazzi ◽  
Marco Pasero ◽  
Federica Zaccarini ◽  
Corrado Balestra ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Empirical Formula ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Ore Deposit ◽  
Cell Parameters ◽  
Homogeneous Domains ◽  
Mn Ore

Two new monoclinic (P21/m) epidote supergroup minerals manganiakasakaite-(La) and ferriakasakaite-(Ce) were found in the small Mn ore deposit of Monte Maniglia, Bellino, Varaita Valley, Cuneo Province, Piedmont, Italy. Manganiakasakaite-(La) occurs as subhedral grains embedded in pyroxmangite. Its empirical formula is A(1)(Ca0.62Mn2+0.38) A(2)(La0.52Nd0.08Pr0.07Ce0.07Y0.01Ca0.25) M(1)(Mn3+0.52Fe3+0.28Al0.18V3+0.01) M(2)Al1.00 M(3)(Mn2+0.60Mn3+0.27Mg0.13) T(1−3)(Si2.99Al0.01) O12 (OH), corresponding to the end-member formula CaLaMn3+AlMn2+(Si2O7)(SiO4)O(OH). Unit-cell parameters are a = 8.9057(10), b = 5.7294(6), c = 10.1134(11) Å, β = 113.713(5)°, V = 472.46(9) Å3, Z = 2. The crystal structure of manganiakasakaite-(La) was refined to a final R1 = 0.0262 for 2119 reflections with Fo > 4σ(Fo) and 125 refined parameters. Ferriakasakaite-(Ce) occurs as small homogeneous domains within strongly inhomogeneous prismatic crystals, where other epidote supergroup minerals coexist [manganiandrosite-(Ce), “androsite-(Ce)”, and epidote]. Associated minerals are calcite and hematite. Its empirical formula is A(1)(Ca0.64Mn2+0.36) A(2)(Ce0.37La0.17Nd0.06Pr0.03Ca0.35□0.02) M(1)(Fe3+0.61Al0.39) M(2)Al1.00 M(3)(Mn2+0.64Mn3+0.33Fe3+0.02Mg0.01) T(1−3)Si3.01 O12 (OH), the end-member formula being CaCeFe3+AlMn2+(Si2O7)(SiO4)O(OH). Unit-cell parameters are a = 8.9033(3), b = 5.7066(2), c = 10.1363(3) Å, β = 114.222(2)°, V = 469.66(3) Å3, Z = 2. The crystal structure of ferriakasakaite-(Ce) was refined to a final R1 = 0.0196 for 1960 unique reflections with Fo > 4σ(Fo) and 124 refined parameters.

Notes on leucophanite from the Ilímaussaq alkaline complex, South Greenland

2001 ◽  
pp. 119-121 ◽  
Author(s):  
Henning Bohse ◽  
Ole V. Petersen ◽  
Gerhard Niedermayr
Keyword(s):  
Empirical Formula ◽  
Unit Cell ◽  
Alkaline Complex ◽  
Unit Cell Parameters ◽  
Widespread Occurrence ◽  
Limited Distribution ◽  
Original Series ◽  
Cell Parameters

 NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Bohse, H., Petersen, O. V., & Niedermayr, G. (2001). Notes on leucophanite from the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin, 190, 119-121. https://doi.org/10.34194/ggub.v190.5180 _______________ Leucophanite from the Ilímaussaq alkaline complex was first described in 1905. For nearly 60 years it was believed to be rare and of very limited distribution in Ilímaussaq, but it has lately proved to be of relatively widespread occurrence. Detailed descriptions of the various occurrences are given. The crystals show the forms {001}, {110}, {101}, {102}, {111} and {113}; all the crystals are twinned either along (110) or (010). Optically the Ilímaussaq leucophanite is biaxial with 2Vα (measured) = 40°; α = 1.575, β = γ = 1.597. The empirical formula, calculated on the basis of Si + Al = 4, is: (Ca1.97Mg0.05REE0.06)Σ2.08(Na2.13K0.01)Σ2.14Be1.92(Si3.88Al0.12)Σ4.00O12.01(F1.87OH0.19)Σ2.06. Unit cell parameters determined on the newly found material are a = 7.38–7.40, b = 7.40–7.41, c = 9.96–9.95, all ± 0.01 Å (Kangerluarsuk) and a = 7.43, b = 7.43, c = 9.90, all ± 0.01 Å (Nakkaalaaq). Thus, a full set of data for the Ilímaussaq leucophanite is now available.

scholarly journals Böhmit a doprovodná zeolitová mineralizace ze Soutěsek u Děčína (Česká republika)

2021 ◽  
Vol 29 (1) ◽  
pp. 164-177
Author(s):  
Petr Pauliš ◽  
Libor Hrůzek ◽  
Oldřich Janeček ◽  
Zdeněk Dolníček ◽  
Luboš Vrtiška ◽  
...  
Keyword(s):  
Czech Republic ◽  
Empirical Formula ◽  
Unit Cell ◽  
Chemical Analyses ◽  
Altered Rock ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
The Town

A new locality of böhmite and zeolite minerals, called „Soutěsky above the quarry“, occurs near the quarry „Soutěsky“ on the SW slope of the Hlídka hill, eastward of the Soutěsky village, about 5 km SW od the town of Děčín (Czech Republic). The mineralization is bound to vugs of Cenozoic volcanics. Böhmite forms mostly whitish to brownish hemispherical to spherical clusters up to 5 mm in size. The unit-cell parameters of böhmite, refined from the X-ray powder data, are a 2.871 (3), b 12.216(9), c 3.699(4) Å and V 129.7(2) Å3. Chemical analyses correspond to the empirical formula (Al0.92 Si0.06)Σ0.98O(OH). The following zeolites have been found in association with böhmite: thomsonite-Ca, phillipsite-K, gismondine, chabazite-Ca and analcime, as well as calcite. Minerals crystallized in following succession: calcite I → phillipsite-K → böhmite → calcite II → thomsonite-Ca → gismondine → calcite III. Independently, (older) analcime and (younger) chabazite-Ca occur. These minerals probably crystallized from low tempered solutions, enriched in Al ions and alkalies, the source of which can be found in altered rock-forming alumosilicates (analcime, nepheline).

scholarly journals Faujasit-Na a doprovodná zeolitová mineralizace z lokality Klučky u Polevska v Lužických horách (Česká republika)

2020 ◽  
Vol 28 (2) ◽  
pp. 417-436
Author(s):  
Petr Pauliš ◽  
Libor Hrůzek ◽  
Oldřich Janeček ◽  
Jiří Sejkora ◽  
Zdeněk Dolníček ◽  
...  
Keyword(s):  
Empirical Formula ◽  
Cell Parameter ◽  
High Elevation ◽  
Unit Cell ◽  
Chemical Analyses ◽  
The Czech Republic ◽  
X Ray ◽  
Cell Parameters ◽  
Basaltic Rocks ◽  
First Occurrence

Four new zeolite occurrences have been discovered in a forested, 3 km long ridge Klučky, composed of basaltic rocks and culminating in the 642 m high elevation of the same name NW of the Nový Bor town in the Lužické hory Mts. At the Wachstein locality, the first occurrence of the rare zeolite faujasite-Na in the Czech Republic was verified. It forms octahedral crystals up to 0.3 mm in size with common twins according to spinel law. The unit-cell parameter of faujasite-Na refined from the powder X-ray data is a 24.6775(9) Å and V 15028.1(9) Å3. Its chemical analyses correspond to the empirical formula (Na1.43Ca1.20K0.44Mg0.16)Σ3.23(Al3.33Si8.36)O24·15 H2O. Besides to phillipsite and chabazite, frequent offretite, characterised by its extraordinary morphological variety, is present in all described localities. The unit-cell parameters of offretite refined from the powder X-ray data are: a 13.311(6), c 7.5934(6) Å and V 1165.2(5) Å3 (Wachstein) and a 13.310(5), c 7.5886(5) Å and V 1164.3(4) Å3 (Klučky - Stráň). Chemical analyses of offretite correspond to the empirical formula K2.02Ca1.31Mg0.32Sr0.09(Al5.42Si12.56)O36·16 H2O (Wachstein) and Ca1.48K1.02Mg0.59Na0.10Sr0.09(Al5.56Si12.52)O36·16 H2O (Klučky - Stráň).

scholarly journals Crystal structures of synthetic 7 Å and 10 Å manganates substituted by mono- and divalent cations

1994 ◽  
Vol 58 (392) ◽  
pp. 425-447 ◽  
Author(s):  
Kenshi Kuma ◽  
Akira Usui ◽  
William Paplawsky ◽  
Benjamin Gedulin ◽  
Gustaf Arrhenius
Keyword(s):  
Crystal Structures ◽  
Diffraction Data ◽  
Divalent Cations ◽  
Unit Cell ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Cell Parameters

AbstractThe crystal structures of synthetic 7 Å and 10 Å manganates, synthetic birnessite and buserite, substituted by mono- and divalent cations were investigated by X-ray and electron diffractions. The monoclinic unit cell parameters of the subcell of lithium 7 Å manganate, which is one of the best ordered manganates, were obtained by computing the X-ray powder diffraction data: a = 5.152 Å, b = 2.845 Å, c = 7.196 Å, β = 103.08°. On the basis of the indices obtained by computing the X-ray diffraction data of Li 7 Å manganate, monovalent Na, K and Cs and divalent Be, Sr and Ba 7 Å manganates were interpreted as the same monoclinic structure with β = 100–103° as that of Li 7 Å manganate, from their X-ray diffraction data. In addition, divalent Mg, Ca and Ni 10 Å manganates were also interpreted as the same monoclinic crystal system with β = 90–94° The unit cell parameters, especially a, c and β, change possibly with the type of substituent cation probably because of the different ionic radius, hydration energy and molar ratio of substituent cation to manganese. However, these diffraction data, except for those of Sr and Ba 7 Å and Ca and Ni 10 Å manganates, reveal only some parts of the host manganese structure with the edge-shared [MnO6] octahedral layer. On the other hand, one of the superlattice reflections observed in the electron diffractions was found in the X-ray diffraction lines for heavier divalent cations Sr and Ba 7 Å and Ca and Ni 10 Å manganates. The reflection presumably results from the substituent cation position in the interlayer which is associated with the vacancies in the edge-shared [MnO6] layer and indicates that the essential vacancies are linearly arranged parallel to the b-axis. Furthermore, the characteristic superlattice reflection patterns for several cations, Li, Mg, Ca, Sr, Ba and Ni, manganates were interpreted that the substituent cations are regularly distributed in the interlayer according to the exchange percentage of substituent cation to Na+. In contrast, the streaking in the a-direction observed strongly in the electron diffractions for heavier monovalent cations, K and Cs, manganates probably results from the disordering of their cations in the a-direction in the interlayer.

scholarly journals Ellinaite, CaCr<sub>2</sub>O<sub>4</sub>, a new natural post-spinel oxide from Hatrurim Basin, Israel, and Juína kimberlite field, Brazil

2021 ◽  
Vol 33 (6) ◽  
pp. 727-742
Author(s):  
Victor V. Sharygin ◽  
Sergey N. Britvin ◽  
Felix V. Kaminsky ◽  
Richard Wirth ◽  
Elena N. Nigmatulina ◽  
...  
Keyword(s):  
Empirical Formula ◽  
Spinel Phase ◽  
Iron Carbide ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Near Surface ◽  
Space Group ◽  
Cell Parameters ◽  
Natural Analog ◽  
Kimberlite Field

Abstract. Ellinaite, a natural analog of the post-spinel phase β-CaCr2O4, was discovered at the Hatrurim Basin, Hatrurim pyrometamorphic formation (the Mottled Zone), Israel, and in an inclusion within the super-deep diamond collected at the placer of the Sorriso River, Juína kimberlite field, Brazil. Ellinaite at the Hatrurim Basin is confined to a reduced rankinite–gehlenite paralava, where it occurs as subhedral grains up to 30 µm in association with gehlenite, rankinite and pyrrhotite or forms the rims overgrowing zoned chromite–magnesiochromite. The empirical formula of the Hatrurim sample is (Ca0.960Fe0.0162+Na0.012Mg0.003)0.992(Cr1.731V0.1833+Ti0.0683+Al0.023Ti0.0034+)2.008O4. The mineral crystallizes in the orthorhombic system, space group Pnma, unit-cell parameters refined from X-ray single-crystal data: a 8.868(9), b 2.885(3), c 10.355(11) Å, V 264.9(5) Å3 and Z=4. The crystal structure of ellinaite from the Hatrurim Basin has been solved and refined to R1=0.0588 based on 388 independent observed reflections. Ellinaite in the Juína diamond occurs within the micron-sized polyphase inclusion in association with ferropericlase, magnesioferrite, orthorhombic MgCr2O4, unidentified iron carbide and graphite. Its empirical formula is Ca1.07(Cr1.71Fe0.063+V0.06Ti0.03Al0.03Mg0.02Mn0.02)Σ1.93O4. The unit-cell parameters obtained from HRTEM data are as follows: space group Pnma, a 9.017, b 2.874 Å, c 10.170 Å, V 263.55 Å3, Z=4. Ellinaite belongs to a group of natural tunnel-structured oxides of the general formula AB2O4, the so-called post-spinel minerals: marokite CaMn2O4, xieite FeCr2O4, harmunite CaFe2O4, wernerkrauseite CaFe23+Mn4+O6, chenmingite FeCr2O4, maohokite MgFe2O4 and tschaunerite Fe(FeTi)O4. The mineral from both occurrences seems to be crystallized under highly reduced conditions at high temperatures (>1000 ∘C), but under different pressure: near-surface (Hatrurim Basin) and lower mantle (Juína diamond).

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