scholarly journals Fogoite-(Y), Na3Ca2Y2Ti(Si2O7)2OF3, a Group I TS-block mineral from the Lagoa do Fogo, the Fogo volcano, São Miguel Island, the Azores: Description and crystal structure

2017 ◽  
Vol 81 (2) ◽  
pp. 369-381 ◽  
Author(s):  
F. Cámara ◽  
E. Sokolova ◽  
Y. A. Abdu ◽  
F. C. Hawthorne ◽  
T. Charrier ◽  
...  
Keyword(s):  
Crystal Structure ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Titanium Silicate ◽  
Triclinic Space Group ◽  
X Ray ◽  
Group I ◽  
Mohs Hardness ◽  
Fogo Volcano ◽  
The Ideal

AbstractFogoite-(Y), Na3Ca2Y2Ti(Si2O7)2OF3, is a new mineral from the Lagoa do Fogo, São Miguel Island, the Azores. It occurs in cavities as highly elongated (on [001]) prisms, up to 2000 μm long and 50 μm× 50 μm in cross-section, associated with sanidine, astrophyllite, fluornatropyrochlore, ferrokentbrooksite, quartz and ferro-katophorite. Crystals are generally transparent and colourless, with vitreous lustre, occasionally creamy white. Fogoite-(Y) has a white streak, splintery fracture and very good {100} cleavage. Mohs hardness is ∼5. Dcalc. = 3.523 g/cm3. It is biaxial (+) with refractive indices (λ = 590 nm) α = 1.686(2), β = 1.690(2), γ = 1.702(5); 2Vmeas. = 57(1)° and 2Vcalc. = 60°. It is nonpleochroic. Fogoite-(Y) is triclinic, space group P1, a = 9.575(6), b = 5.685(4), c = 7.279(5) Å, α = 89.985(6), β = 100.933(4), γ = 101.300(5)°, V = 381.2 (7) Å3. The six strongest reflections in the powder X-ray diffraction data [d (Å), I, (hkl)] are: 2.954, 100, (1̄1̄2, 3̄10); 3.069, 42, (300, 01̄2); 2.486, 24, (310, 21̄2); 3.960, 23, (1̄1̄1, 2̄10); 2.626, 21, (2̄20); 1.820, 20, (1̄04). Electron microprobe analysis gave the following empirical formula calculated on 18 (O + F) (Na2.74Mn0.15)∑2.89Ca2[Y1.21(La0.01Ce0.03Nd0.03Sm0.02Gd0.08Dy0.08Er0.05Yb0.04Lu0.01)∑0.35Mn0.16Zr0.11Na0.09Fe0.072+Ca0.01]∑2(Ti0.76Nb0.23Ta0.01)∑1(Si4.03O14)O1.12F2.88, Z = 1. The crystal structure was refined on a twinnedcrystal to R1 = 2.81% on the basis of 2157 unique reflections (Fo > 4σFo) and is a framework of TS (Titanium Silicate) blocks, which consist of HOH sheets (H – heteropolyhedral, O – octahedral) parallel to (100). In the O sheet, the the [6]MO(1) site is occupied mainly by Ti, <MO(1)–ϕ> = 1.980 Å, and the [6]MO(2) and [6]MO(3) sites are occupied by Na and Na plus minor Mn, <MO(2)–ϕ>= 2.490 Å and <MO(3)–ϕ> = 2.378 Å. In the H sheet, the two [4]Si sites are occupied by Si, with <Si–O> = 1.623 Å; the [6]MH site is occupied by Y and rare-earth elements (Y > REE), with minor Mn, Zr, Na, Fe2+ and Ca, <MH–ϕ> = 2.271 Å and the [6]AP site is occupied by Ca, <AP–ϕ> = 2.416 Å. The MH and AP octahedra and Si2O7 groups constitute the H sheet. The ideal compositions of the O and two H sheets are Na3Ti(OF)F2 and Y2Ca2(Si2O7)2 apfu. Fogoite-(Y) is isostructural with götzenite and hainite. The mineral is named after the type locality, the Fogo volcano in the Azores.

Antipinite, KNa3Cu2(C2O4)4, a new mineral species from a guano deposit at Pabellón de Pica, Chile

2015 ◽  
Vol 79 (5) ◽  
pp. 1111-1121 ◽  
Author(s):  
Nikita V. Chukanov ◽  
Sergey M. Aksenov ◽  
Ramiza K. Rastsvetaeva ◽  
Konstantin A. Lyssenko ◽  
Dmitriy I. Belakovskiy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gas Chromatography ◽  
Chemical Composition ◽  
Infrared Spectrum ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
New Mineral Species ◽  
Mohs Hardness

AbstractThe new oxalate mineral antipinite is found in a guano deposit located on the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile. Associated minerals are halite, salammoniac, chanabayaite, joanneumite and clays. Antipinite occurs as blue, imperfect, short prismatic crystals up to 0.1 mm × 0.1 mm × 0.15 mm in size, as well as their clusters and random aggregates. The mineral is brittle. Mohs hardness is 2; Dmeas = 2.53(3), Dcalc = 2.549 g cm–3. The infrared spectrum shows the presence of oxalate anions and the absence of absorptions associated with H2O molecules, C–H bonds, CO32–, NO3– and OH– ions. Antipinite is optically biaxial (+), α = 1.432(3), β = 1.530(1), γ = 1.698(5), 2Vmeas = 75(10)°, 2Vcalc = 82°. The chemical composition (electron-microprobe data, C measured by gas chromatography of products of ignition at 1200°C, wt.%) is Na2O 15.95, K2O 5.65, CuO 27.34, C2O3 48.64, total 99.58. The empirical formula is K0.96Na3.04Cu2.03(C2.00O4)4 and the idealized formula is KNa3Cu2(C2O4)4. The crystal structure was solved and refined to R = 0.033 based upon 4085 unique reflections with I > 2σ(I). Antipinite is triclinic, space group P1, a = 7.1574(5), b = 10.7099(8), c = 11.1320(8) Å, α = 113.093(1), β = 101.294(1), γ = 90.335 (1)°, V = 766.51(3) Å3, Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d, Å (I,%) (hkl)] are 5.22 (40) (111), 3.47 (100) (032), 3.39 (80) (210), 3.01 (30) (033, 220), 2.543 (40) (122, 034, 104), 2.481 (30) (213), 2.315 (30) (143, 310), 1.629 (30) (146, 414, 243, 160).

scholarly journals Richardsite, Zn2CuGaS4, A New Gallium-Essential Member of the Stannite Group from the Gem Mines near Merelani, Tanzania

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 467 ◽  
Author(s):  
Luca Bindi ◽  
John A. Jaszczak
Keyword(s):  
Crystal Structure ◽  
Polarized Light ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
International Mineralogical Association ◽  
Metal Atoms ◽  
Group I ◽  
The Ideal

The new mineral richardsite occurs as overgrowths of small (50–400 μm) dark gray, disphenoidal crystals with no evident twinning, but epitaxically oriented on wurtzite–sphalerite crystals from the gem mines near Merelani, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania. Associated minerals also include graphite, diopside, and Ge,Ga-rich wurtzite. It is brittle, dark gray in color, and has a metallic luster. It appears dark bluish gray in reflected plane-polarized light, and is moderately bireflectant. It is distinctly anisotropic with violet to light-blue rotation tints with crossed polarizers. Reflectance percentages for Rmin and Rmax in air at the respective wavelengths are 23.5, 25.0 (471.1 nm); 27.4, 28.9 (548.3 nm); 28.1, 29.4 (586.6 nm); 27.7, 28.9 (652.3 nm). Richardsite does not show pleochroism, internal reflections, or optical indications of growth zonation. Electron microprobe analyses determine an empirical formula, based on 8 apfu, as (Zn1.975Cu0.995Ga0.995Fe0.025Mn0.010Ge0.005Sn0.005)Σ4.010S3.990, while its simplified formula is (Zn,Cu)2(Cu,Fe,Mn)(Ga,Ge,Sn)S4, and the ideal formula is Zn2CuGaS4. The crystal structure of richardsite was investigated using single-crystal and powder X-ray diffraction. It is tetragonal, with a = 5.3626(2) Å, c = 10.5873(5) Å, V = 304.46(2) Å3, Z = 2, and a calculated density of 4.278 g·cm−3. The four most intense X-ray powder diffraction lines [d in Å (I/I0)] are 3.084 (100); 1.882 (40); 1.989 (20); 1.614 (20). The refined crystal structure (R1 = 0.0284 for 655 reflections) and obtained chemical formula indicate that richardsite is a new member of the stannite group with space group I 4 ¯ 2 m . Its structure consists of a ccp array of sulfur atoms tetrahedrally bonded with metal atoms occupying one-half of the ccp tetrahedral voids. The ordering of the metal atoms leads to a sphalerite(sph)-derivative tetragonal unit-cell, with a ≈ asph and c ≈ 2asph. The packing of S atoms slightly deviates from the ideal, mainly due to the presence of Ga. Using 632.8-nm wavelength laser excitation, the most intense Raman response is a narrow peak at 309 cm−1, with other relatively strong bands at 276, 350, and 366 cm−1, and broader and weaker bands at 172, 676, and 722 cm−1. Richardsite is named in honor of Dr. R. Peter Richards in recognition of his extensive research and writing on topics related to understanding the genesis of the morphology of minerals. Its status as a new mineral and its name have been approved by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association (No. 2019-136).

Hrabákite, Ni9PbSbS8, a new member of the hauchecornite group from Příbram, Czech Republic

2021 ◽  
pp. 1-8
Author(s):  
Jiří Sejkora ◽  
Pavel Škácha ◽  
Jakub Plášil ◽  
Zdeněk Dolníček ◽  
Jana Ulmanová
Keyword(s):  
Czech Republic ◽  
Diffraction Data ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
Reflected Light ◽  
Mohs Hardness ◽  
Cation Sites ◽  
The Ideal

Abstract The new mineral hrabákite (IMA2020-034) was found in siderite–sphalerite gangue with minor dolomite–ankerite at the dump of shaft No. 9, one of the mines in the abandoned Příbram uranium and base-metal district, central Bohemia, Czech Republic. Hrabákite is associated with Pb-rich tučekite, Hg-rich silver, stephanite, nickeline, millerite, gersdorffite, sphalerite and galena. The new mineral occurs as rare prismatic crystals up to 120 μm in size and allotriomorphic grains. Hrabákite is grey with a brownish tint. Mohs hardness is ca. 5–6; the calculated density is 6.37 g.cm–3. In reflected light, hrabákite is grey with a brown hue. Bireflectance is weak and pleochroism was not observed. Anisotropy under crossed polars is very weak (brownish tints) to absent. Internal reflections were not observed. Reflectance values of hrabákite in air (Rmin–Rmax, %) are: 39.6–42.5 at 470 nm, 45.0–47.5 at 546 nm, 46.9–49.2 at 589 nm and 48.9–51.2 at 650 nm). The empirical formula for hrabákite, based on electron-microprobe analyses (n = 11), is (Ni8.91Co0.09Fe0.03)9.03(Pb0.94Hg0.04)0.98(Sb0.91As0.08)0.99S7.99. The ideal formula is Ni9PbSbS8, which requires Ni 47.44, Pb 18.60, Sb 10.93 and S 23.03, total of 100.00 wt.%. Hrabákite is tetragonal, P4/mmm, a = 7.3085(4), c = 5.3969(3) Å, with V = 288.27(3) Å3 and Z = 1. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I)(hkl)] are: 3.6543(57)(200); 3.2685(68)(210); 2.7957(100)(211); 2.3920(87)(112); 2.3112(78)(310); 1.8663(74)(222); and 1.8083(71)(302). According to the single-crystal X-ray diffraction data (Rint = 0.0218), the unit cell of hrabákite is undoubtedly similar to the cell reported for tučekite. The structure contains four metal cation sites, two Sb (Sb1 dominated by Pb2+) and two Ni (with minor Co2+ content) sites. The close similarity in metrics between hrabákite and tučekite is due to similar bond lengths of Pb–S and Sb–S pairs. Hrabákite is named after Josef Hrabák, the former professor of the Příbram Mining College.

Hylbrownite, Na3MgP3O10·12H2O, a new triphosphate mineral from the Dome Rock Mine, South Australia: description and crystal structure

2013 ◽  
Vol 77 (3) ◽  
pp. 385-398 ◽  
Author(s):  
P. Elliott ◽  
J. Brugger ◽  
T. Caradoc-Davies ◽  
A. Pring
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
South Australia ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Thick Sheet ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Mineral Species ◽  
Mohs Hardness

AbstractHylbrownite, ideally Na3MgP3O10·12H2O, the second known triphosphate mineral, is a new mineral species from the Dome Rock mine, Boolcoomatta Reserve, Olary Province, South Australia, Australia. The mineral forms aggregates and sprays of crystals up to 0.5 mm across with individual crystals up to 0.12 mm in length and 0.02 mm in width. Crystals are thin prismatic to acicular in habit and are elongate along [001]. Forms observed are {010}, {100}, {001}, {210} and {201}. Crystals are colourless to white, possess a white streak, are transparent, brittle, have a vitreous lustre and are nonfluorescent. The measured density is 1.81(4) g cm−3; Mohs' hardness was not determined. Cleavage is good parallel to {001} and to {100} and the fracture is uneven. Hylbrownite crystals are nonpleochroic, biaxial (−), with α = 1.390(4), β = 1.421(4), γ = 1.446(4) and 2Vcalc. = 82.2°. Hylbrownite is monoclinic, space group P21/n, with a = 14.722(3), b = 9.240(2), c = 15.052(3) Å, β = 90.01(3)°, V = 2047.5(7) Å3, (single-crystal data) and Z = 4. The strongest lines in the powder X-ray diffraction pattern are [d (Å)(I)(hkl)]: 10.530(60)(10,101), 7.357(80)(200), 6.951(100)(11, 111), 4.754(35)(10, 103), 3.934(40)(022), 3.510(45)(30, 303), 3.336(35)(41, 411). Chemical analysis by electron microprobe gave Na2O 16.08, MgO 7.08, CaO 0.43, P2O5 37.60, H2Ocalc 38.45, total 99.64 wt.%. The empirical formula, calculated on the basis of 22 oxygen atoms is Na2.93Mg0.99Ca0.04P2.99O9.97·12.03H2O. The crystal structure was solved from single-crystal X-ray diffraction data using synchrotron radiation (T = 123 K) and refined to R1 = 4.50% on the basis of 2417 observed reflections with F0 > 4 σ(F0). [Mg(H2O)3P3O10] clusters link in the b direction to Naφ6 octahedra, by face and corner sharing. Edge sharing Naφ6 Octahedra and Naφ7 polyhedra form Na2O9 groups which link via corners to form chains along the b direction. Chains link to [Mg(H2O)3P3O10] clusters via corner-sharing in the c direction and form a thick sheet parallel to (100). Sheets are linked in the a direction via hydrogen bonds.

Khvorovite, Pb2+4Ca2[Si8B2(SiB)O28]F, a new hyalotekite-group mineral from the Darai-Pioz alkaline massif, Tajikistan: Description and crystal structure

2015 ◽  
Vol 79 (4) ◽  
pp. 949-963 ◽  
Author(s):  
Leonid A. Pautov ◽  
Atali A. Agakhanov ◽  
Elena Sokolova ◽  
Frank C. Hawthorne ◽  
Vladimir Y. Karpenko ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Refractive Indices ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Pyrochlore Group ◽  
Mohs Hardness ◽  
Ideal Composition ◽  
Alkaline Massif ◽  
Simplified Formula

AbstractKhvorovite, ideally Pb42+Ca2[Si8B2(SiB)O28]F, is a new borosilicate mineral of the hyalotekite group from the Darai-Pioz alkaline massif in the upper reaches of the Darai-Pioz river, Tajikistan. Khvorovite was found in a pectolite aggregate in silexites (quartz-rich rocks). The pectolite aggregate consists mainly of pectolite, quartz and fluorite, with minor aegirine, polylithionite, turkestanite and baratovite; accessory minerals are calcite, pyrochlore-group minerals, reedmergnerite, stillwellite-(Ce), pekovite, zeravshanite, senkevichite, sokolovaite, mendeleevite-(Ce), alamosite, orlovite, leucosphenite and several unknown Cs-silicates. Khvorovite occurs as irregular grains, rarely with square or rectangular sections up to 150 μm, and grain aggregates up to 0.5 mm. Khvorovite is colourless, rarely white, transparent with a white streak, has a vitreous lustre and does not fluoresce under ultraviolet light. Cleavage and parting were not observed. Mohs hardness is 5–5.5, and khvorovite is brittle with an uneven fracture. The measured and calculated densities are 3.96(2) and 3.968 g/cm3, respectively. Khvorovite is biaxial (+) with refractive indices (λ = 589 nm) α = 1.659(3), βcalc. = 1.671(2), γ = 1.676(3); 2Vmeas. = 64(3)°, medium dispersion: r < v. Khvorovite is triclinic, space group I1¯, a = 11.354(2), b = 10.960(2), c = 10.271(2) Å, α = 90.32(3), β = 90.00(3), γ = 90.00(3)°, V = 1278(1) Å3, Z = 2. The six strongest lines in the powder X-ray diffraction pattern [d (Å), I, (hkl)] are: 7.86, 100, (110); 7.65, 90, (101); 7.55, 90, (011); 3.81, 90, (202); 3.55, 90, (301); 2.934, 90, (312, 312). Chemical analysis by electron microprobe gave SiO2 36.98, B2O3 6.01, Y2O3 0.26, PbO 40.08, BaO 6.18, SrO 0.43, CaO 6.77, K2O 1.72, Na2O 0.41, F 0.88, O=F –0.37, sum 99.35 wt.%. The empirical formula based on 29 (O+F) a.p.f.u. is (Pb2.762+Ba0.62K0.56Na0.16)Σ4.10(Ca1.86Sr0.06Y0.04Na0.04)Σ2[Si8B2(Si1.46B0.65)Σ2.11O28](F0.71O0.29), Z = 2 , and the simplified formula is (Pb2+, Ba, K)4Ca2[Si8B2(Si,B)2O28]F. The crystal structure of khvorovite was refined to R1 = 2.89% based on 3680 observed reflections collected on a four-circle diffractometer with MoKα radiation. In the crystal structure of khvorovite, there are four [4]-coordinated Si sites occupied solely by Si with <Si–O>= 1.617 Å. The [4]-coordinated B site is occupied solely by B, with <B–O> = 1.478 Å. The [4]-coordinated T site is occupied by Si and B (Si1.46B0.54), with <T–O> = 1.605 Å; it ideally gives (SiB) a.p.f.u. The Si, B and T tetrahedra form an interrupted framework of ideal composition [Si8B2(SiB)O28]11–. The interstitial cations are Pb2+, Ba and K (minor Na) [A(11–22) sites] and Ca [M site]. The two A sites are each split into two subsites ∼0.5 Å apart and occupied by Pb2+ and Ba + K. The [8]-coordinated M site is occupied mainly by Ca, with minor Sr, Y and Na. Khvorovite is a Pb2+ analogue of hyalotekite, (Ba,Pb2+,K)4(Ca,Y)2[Si8(B,Be)2(Si,B)2O28]F and a Pb2+-, Ca-analogue of kapitsaite-(Y), (Ba,K)4(Y,Ca)2[Si8B2(B,Si)2O28]F. It is named after Pavel V. Khvorov (b. 1965), a Russian mineralogist, to honour his contribution to the study of the mineralogy of the Darai-Pioz massif.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. VIII. Arsenowagnerite, Mg2(AsO4)F

2018 ◽  
Vol 82 (4) ◽  
pp. 877-888 ◽  
Author(s):  
Igor V. Pekov ◽  
Natalia V. Zubkova ◽  
Atali A. Agakhanov ◽  
Vasiliy O. Yapaskurt ◽  
Nikita V. Chukanov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Scoria Cone ◽  
New Mineral ◽  
Lemon Yellow ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
X Ray ◽  
Light Yellow ◽  
Tolbachik Volcano ◽  
Mohs Hardness

ABSTRACTA new mineral arsenowagnerite, Mg2(AsO4)F, the arsenate analogue of wagnerite, was found in sublimates of 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 closely with johillerite, tilasite, anhydrite, hematite, fluorophlogopite, cassiterite, calciojohillerite, aphthitalite and fluoborite. Arsenowagnerite occurs as equant to tabular crystals up to 1 mm across combined in interrupted crusts up to 0.1 cm × 1.5 cm × 3 cm. The mineral is transparent, light yellow, lemon-yellow, greenish-yellow or colourless and has a vitreous lustre. Arsenowagnerite is brittle, with Mohs hardness of ~5. Cleavage is distinct, the fracture is uneven. Dcalc = 3.70 g cm–3. Arsenowagnerite is optically biaxial (+), α = 1.614(2), β = 1.615(2), γ = 1.640(2) and 2Vmeas = 25(5)°. Wavenumbers of the strongest absorption bands in the IR spectrum (cm–1) are: 874, 861, 507, 491 and 470. The chemical composition (average of six electron-microprobe analyses, wt.%) is: MgO 38.72, CaO 0.23, MnO 0.32, CuO 0.60, ZnO 0.05, Fe2O3 0.11, TiO2 0.03, SiO2 0.08, P2O5 0.18, V2O5 0.03, As2O5 54.96, SO3 0.10, F 8.91 and –O=F –3.75, total 100.57. The empirical formula calculated on the basis of 5 (O + F) apfu is: (Mg1.98Cu0.02Mn0.01Ca0.01)Σ2.02(As0.99P0.01)Σ1.00O4.03F0.97. Arsenowagnerite is monoclinic, P21/c, a = 9.8638(3), b = 12.9830(3), c = 12.3284(3) Å, β = 109.291(3)°, V = 1490.15(7) Å3 and Z = 16. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 5.80(41)(002), 5.31(35)(120), 3.916(37)($\bar 2$21), 3.339(98)(221, 023), 3.155(65)(202), 3.043(100)($\bar 1$41), 2.940(72)($\bar 2$04), 2.879(34)($\bar 3$22) and 2.787(51)(320, $\bar 1$24). The crystal structure was solved from single-crystal X-ray diffraction data, R = 0.0485. Arsenowagnerite is isostructural to wagnerite-Ma2bc. The crystal structure is built by almost regular AsO4 tetrahedra, distorted MgO4F2 octahedra and distorted MgO4F trigonal bipyramids.

Shilovite, natural copper(II) tetrammine nitrate, a new mineral species

2015 ◽  
Vol 79 (3) ◽  
pp. 613-623 ◽  
Author(s):  
Nikita V. Chukanov ◽  
Sergey N. Britvin ◽  
Gerhard Möhn ◽  
Igor V. Pekov ◽  
Natalia V. Zubkova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Infrared Spectrum ◽  
Copper Complex ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
New Mineral Species ◽  
Mohs Hardness

AbstractThe new mineral shilovite, the first natural tetrammine copper complex, was found in a guano deposit located on the Pabellón de Pica Mountain, near Chanabaya, Iquique Province, Tarapacá Region, Chile. It is associated with halite, ammineite, atacamite (a product of ammineite alteration) and thénardite. The gabbro host rock consists of amphibole, plagioclase and minor clinochlore, and contains accessory chalcopyrite. The latter is considered the source of Cu for shilovite. The new mineral occurs as deep violet blue, imperfect, thick tabular to equant crystals up to 0.15 mm in size included in massive halite. The mineral is sectile. Its Mohs hardness is 2. Dcalc is 1.92 g cm–3. The infrared spectrum shows the presence of NH3 molecules and NO3– anions. Shilovite is optically biaxial (+), α = 1.527(2), β = 1.545(5), γ = 1.610(2). The chemical composition (electron-microprobe data, H calculated from ideal formula, wt.%) is Cu 26.04, Fe 0.31, N 30.8, O 35.95, H 4.74, total 100.69. The empirical formula is H12.56(Cu1.09Fe0.01)N5.87O6.00. The idealized formula is Cu(NH3)4(NO3)2. The crystal structure was solved and refined to R = 0.029 based upon 2705 unique reflections having F > 4σ(F). Shilovite is orthorhombic, space group Pnn2, a = 23.6585(9), b = 10.8238(4), c = 6.9054(3) Å, V = 1768.3(1) Å3, Z = 8. The strongest reflections of the powder X-ray diffraction pattern [d, Å (I,%) (hkl)] are: 5.931 (41) (400), 5.841 (100) (011), 5.208 (47) (410), 4.162 (88) (411), 4.005 (62) (420), 3.462 (50) (002), 3.207 (32) (031), 2.811 (40) (412).

Chukotkaite, AgPb7Sb5S15, a new sulfosalt mineral from Eastern Chukotka, Russia

2020 ◽  
Vol 58 (5) ◽  
pp. 587-596
Author(s):  
Anatoly V. Kasatkin ◽  
Emil Makovicky ◽  
Jakub Plášil ◽  
Radek Škoda ◽  
Atali A. Agakhanov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Eastern Region ◽  
X Ray Diffraction ◽  
Metallic Luster ◽  
X Ray ◽  
Reflected Light ◽  
North Eastern ◽  
Mohs Hardness

ABSTRACT The new sulfosalt chukotkaite, ideally AgPb7Sb5S15, was discovered in the valley of the Levyi Vulvyveem river, Amguema river basin, Iultin District, Eastern Chukotka, Chukotka Autonomous Okrug, North-Eastern region, Russia. The new mineral forms anhedral grains up to 0.4 × 0.5 mm intergrown with pyrrhotite, sphalerite, galena, stannite, quartz, and Mn-Fe-bearing clinochlore. Other associated minerals include arsenopyrite, benavidesite, diaphorite, jamesonite, owyheeite, uchucchacuaite, cassiterite, and fluorapatite. Chukotkaite is lead-grey and has metallic luster and a grey streak. It is brittle and has an uneven fracture. Neither cleavage nor parting were observed. Mohs hardness is 2–2½. Dcalc. = 6.255 g/cm3. In reflected light, chukotkaite is white, moderately anisotropic with rotation tints varying from bluish-grey to brownish-grey. No pleochroism or internal reflections are observed. The chemical composition of chukotkaite is (wt.%; electron microprobe) Ag 3.83, Pb 53.67, Sb 24.30, S 18.46, total 100.26. The empirical formula based on the sum of all atoms = 28 pfu is Ag0.93Pb6.78Sb5.22S15.07. Chukotkaite is monoclinic, space group P21/c, a = 4.0575(3), b = 35.9502(11), c = 19.2215(19) Å, β = 90.525(8)°, V = 2803.7(4) Å3, and Z = 4. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 3.52 (100) (045), 3.38 (50) (055), 3.13 (50) (065), , 2.82 (25) (066), 1.91 (50) (0 1 10). The crystal structure of chukotkaite was refined from single-crystal X-ray diffraction data to R = 0.0712 for 3307 observed reflections with Iobs &gt; 3σ(I). Chukotkaite belongs to the group of rod-based sulfosalts. The new mineral is named after the region of its type locality: Chukotka Autonomous Okrug, North-Eastern Region, Russia.

Die Kristallstrukturen von PPh4[SnCl3] und PPh4[SnBr3]/ The Crystal Structures of PPh4[SnCl3] and PPh4[SnBr3]

1982 ◽  
Vol 37 (9) ◽  
pp. 1122-1126 ◽  
Author(s):  
Ulrich Müller ◽  
Norbert Mronga ◽  
Christina Schumacher ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Vibrational Spectra ◽  
Diffraction Data ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Structure Determinations ◽  
The Ideal

AbstractPPh4[SnCl3] and PPh4[SnBr3] were prepared by reaction of PPh4X with SnX2 in CH2X2 solutions (X - Cl, Br). The vibrational spectra of the [SnX3]⊖ ions show three SnX3 stretching frequencies, which is caused by deviations from the ideal C3v symmetry. In the crystal structure determinations these deviations show up by slightly different Sn-X bond lengths which are explained by differing hydrogen bridges to phenyl-H atoms. The isotypic crystal structures of both compounds were determined and refined from X-ray diffraction data (R values: 0.042 and 0.034). Although triclinic (space group P1̄), the structures are closely related to the tetragonal AsPh4[RuNCl4] structure type. Very pure SnBr2 is prepared by the reaction of PPh4[SnBr3] with AlBr3 in CH2Br2 solution.

Antofagastaite, Na2Ca(SO4)2·1.5H2O, a new mineral related to syngenite

2019 ◽  
Vol 83 (6) ◽  
pp. 781-790
Author(s):  
Igor V. Pekov ◽  
Vadim M. Kovrugin ◽  
Oleg I. Siidra ◽  
Nikita V. Chukanov ◽  
Dmitry I. Belakovskiy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
New Mineral ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Quartz Veins ◽  
Tolbachik Volcano ◽  
Mohs Hardness ◽  
The One

AbstractThe new mineral antofagastaite, ideally Na2Ca(SO4)2·1.5H2O, was found in the oxidation zone of sulfide–quartz veins at the abandoned Coronel Manuel Rodríguez mine, Mejillones, Antofagasta Province, Antofagasta Region, Chile. It is associated with sideronatrite, metasideronatrite, aubertite, gypsum, ferrinatrite, glauberite, amarillite and an unidentified Fe phosphate. Antofagastaite occurs as prismatic crystals up to 0.5 mm × 1 mm × 5 mm, elongated along [010], typically combined in open-work aggregates up to 1 cm across. Antofagastaite is transparent and colourless, with vitreous lustre. It is brittle; the Mohs’ hardness isca3. Cleavage is distinct on (001).Dmeas.is 2.42(1) andDcalc.is 2.465 g cm−3. Antofagastaite is optically biaxial (–), α = 1.489(2), β = 1.508(2), γ = 1.510(2) and 2Vmeas.= 40(10)°. The IR spectrum is reported. Chemical composition (wt.%, electron microprobe, H2O determined by gas chromatography) is: Na2O 20.85, CaO 17.42, SO352.56, H2O 7.93, total 98.76. The empirical formula (based on 8 O atoms belonging to sulfate anions per formula unit with all H belonging to H2O molecules) is Na2.06Ca0.95S2.01O8·1.35H2O. Antofagastaite is monoclinic,P21/m,a= 6.4596(4),b= 6.8703(5),c= 9.4685(7) Å, β = 104.580(4)°,V= 406.67(5) Å3andZ= 2. The strongest reflections of the powder XRD pattern [d, Å (I, %) (hkl)] are: 9.17 (100) (001), 5.501 (57) (011), 3.437 (59) (020), 3.058 (43) (003), 2.918 (50) (2¯11), 2.795 (35) (013) and 2.753 (50) (121, 201). The crystal structure was solved based on single-crystal X-ray diffraction data,R1= 5.71%. The structure of antofagastaite consists of ordered and disordered blocks and is related to syngenite K2Ca(SO4)2·H2O. Incorporation of additional H2O molecules in the syngenite-type structure results in disorder of the one of the two tetrahedral sulfate groups occurring in antofagastaite. In addition to the above-reported type material, antofagastaite together with syngenite and blödite occurs in the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia.

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