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).

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.

Katophorite from the Jade Mine Tract, Myanmar: mineral description of a rare (grandfathered) endmember of the amphibole supergroup

2015 ◽  
Vol 79 (2) ◽  
pp. 355-363 ◽  
Author(s):  
Roberta Oberti ◽  
Massimo Boiocchi ◽  
Frank C. Hawthorne ◽  
Neil A. Ball ◽  
George E. Harlow
Keyword(s):  
Microprobe Analysis ◽  
Structure Refinement ◽  
Polarized Light ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
International Mineralogical Association ◽  
Compositional Field ◽  
The Ideal

AbstractKatophorite has the ideal formula ANaB(NaCa)C(Mg4Al)T(Si7Al)O22W(OH)2 (Hawthorne et al., 2012). No published analyses of amphiboles fall in the katophorite compositional field, except that of Harlow and Olds (1987) for an amphibole from near Hpakan in the Jade Mine Tract, Myanmar. This amphibole was approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (vote 2013-140) as katophorite, and is reported here. Holotype katophorite is monoclinic, space group C2/m, a = 9.8573(8), b = 17.9617(15), c = 5.2833(4) Å, β = 104.707(2)°, V = 904.78(13) Å3, Z = 2. The calculated density is 3.091 g cm–3. In plane-polarized light, katophorite is pleochroic, X = pale blue (medium), Y = light blue-green (strongest), Z = colourless; X ∧ a = 30.6° (β obtuse), Y || b, Z ∧ c = 15.8 (β acute). It is biaxial negative, α = 1.638, β = 1.642, γ = 1.644, all ± 0.002; 2Vobs = 73(1)°, 2Vcalc = 70°. The eight strongest lines in the powder X-ray diffraction pattern are [d in Å (I)(hkl)]: 2.700 (100)(151), 3.129 (69)(310), 2.536 (65)(202), 3.378 (61)(131), 8.421 (55)(110), 2.583 (46)(061), 2.942 (43)(221) and 2.334 (41)(351). Electron-microprobe analysis of the refined crystal gave SiO251.74, Al2O37.38, TiO2 0.14, FeO 1.55, Fe2O3 2.82, MgO 18.09, CaO 8.17, Na2O 6.02, K2O 0.24, F 0.06, H2Ocalc. 1.80, Li2Ocalc. 0.09, sum 100.55 wt.% (Li2O and H2O based on the results of single-crystal structure refinement). The formula unit, calculated on the basis of 24 (O,OH,F) with (OH + F + O) = 2 is: A(Na0.85K0.04)Σ=0.89B(Ca1.22Na0.78)Σ=2.00C(Mg3.76Al0.43Fe0.303+Cr0.273+Fe0.182+Li0.05Ti0.014+)Σ=5.00T(Si7.21Al0.79)Σ=8.00O22W[(OH)1.67O0.30F0.03)]Σ=2.00.

Arrheniusite-(Ce), CaMg[(Ce7Y3)Ca5](SiO4)3(Si3B3O18)(AsO4)(BO3)F11, a New Member of the Vicanite Group, from the Östanmossa Mine, Norberg, Sweden

2021 ◽  
Author(s):  
Dan Holtstam ◽  
Luca Bindi ◽  
Paola Bonazzi ◽  
Hans-Jürgen Förster ◽  
Ulf B. Andersson
Keyword(s):  
Structure Refinement ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
Epma Data ◽  
X Ray ◽  
Cell Parameters ◽  
Greenish Yellow ◽  
The Ideal

ABSTRACT Arrheniusite-(Ce) is a new mineral (IMA 2019-086) from the Östanmossa mine, one of the Bastnäs-type deposits in the Bergslagen ore region, Sweden. It occurs in a metasomatic F-rich skarn, associated with dolomite, tremolite, talc, magnetite, calcite, pyrite, dollaseite-(Ce), parisite-(Ce), bastnäsite-(Ce), fluorbritholite-(Ce), and gadolinite-(Nd). Arrheniusite-(Ce) forms anhedral, greenish-yellow translucent grains, exceptionally up to 0.8 mm in diameter. It is optically uniaxial (–), with ω = 1.750(5), ε = 1.725(5), and non-pleochroic in thin section. The calculated density is 4.78(1) g/cm3. Arrheniusite-(Ce) is trigonal, space group R3m, with unit-cell parameters a = 10.8082(3) Å, c = 27.5196(9) Å, and V = 2784.07(14) Å3 for Z = 3. The crystal structure was refined from X-ray diffraction data to R1 = 3.85% for 2286 observed reflections [Fo &gt; 4σ(Fo)]. The empirical formula for the fragment used for the structural study, based on EPMA data and results from the structure refinement, is: (Ca0.65As3+0.35)Σ1(Mg0.57Fe2+0.30As5+0.10Al0.03)Σ1[(Ce2.24Nd2.13La0.86Gd0.74Sm0.71Pr0.37)Σ7.05(Y2.76Dy0.26Er0.11Tb0.08Tm0.01Ho0.04Yb0.01)Σ3.27Ca4.14]Σ14.46(SiO4)3[(Si3.26B2.74)Σ6O17.31F0.69][(As5+0.65Si0.22P0.13)Σ1O4](B0.77O3)F11; the ideal formula obtained is CaMg[(Ce7Y3)Ca5](SiO4)3(Si3B3O18)(AsO4)(BO3)F11. Arrheniusite-(Ce) belongs to the vicanite group of minerals and is distinct from other isostructural members mainly by having a Mg-dominant, octahedrally coordinated site (M6); it can be considered a Mg-As analog to hundholmenite-(Y). The threefold coordinated T5 site is partly occupied by B, like in laptevite-(Ce) and vicanite-(Ce). The mineral name honors C.A. Arrhenius (1757–1824), a Swedish officer and chemist, who first discovered gadolinite-(Y) from the famous Ytterby pegmatite quarry.

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.

Redefinition of thérèsemagnanite, NaCo4(SO4)(OH)6Cl·6H2O: new data and relationship to ‘cobaltogordaite’

2018 ◽  
Vol 82 (1) ◽  
pp. 159-170 ◽  
Author(s):  
Anatoly V. Kasatkin ◽  
Jakub Plášil ◽  
Radek Škoda ◽  
Dmitriy I. Belakovskiy ◽  
Joe Marty ◽  
...  
Keyword(s):  
Crystal Structure Data ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Oh Groups ◽  
X Ray ◽  
International Mineralogical Association ◽  
Mineralogical Association ◽  
Holotype Specimen ◽  
Cl Atoms ◽  
The Ideal

ABSTRACTThérèsemagnanite was originally described from the Cap Garonne mine, Var, France. Its ideal formula was reported as (Co,Zn,Ni)6(SO4)(OH,Cl)10·8H2O; without crystal structure data, only the powder X-ray diffraction pattern was given. Revision of the holotype material revealed that thérèsemagnanite is identical to ‘cobaltogordaite’ (IMA2014-043), recently described from the Blue Lizard mine, Utah, USA. Thérèsemagnanite is thus redefined in accordance with the new data obtained for the neotype specimen from Blue Lizard (formerly the holotype specimen of ‘cobaltogordaite’) and ‘cobaltogordaite’ has been discredited by the International Mineralogical Association Commission on New Mineral Nomenclature and Classification (IMA CNMNC). Thérèsemagnanite has the ideal, end-member formula NaCo4(SO4)(OH)6Cl·6H2O. The empirical formulae of the holotype (Cap Garonne) and the neotype (Blue Lizard), both based on microprobe analyses and calculated on the basis of 17 O + Cl atoms per formula unit (with fixed 6 OH groups and 6 H2O molecules; H content is calculated by stoichiometry) are (Na0.64K0.09)Σ0.73(Co2.35Zn1.22Ni0.50)Σ4.07S1.02O3.98(OH)6Cl1.02·6H2O and Na1.01(Co1.90Zn1.37Ni0.48Cu0.15Mn0.05)Σ3.95S1.03O4.09(OH)6Cl0.91·6H2O, respectively. Thérèsemagnanite is trigonal,P$\overline 3 $,a= 8.349(3),c= 13.031(2) Å,V= 786.6(4) Å3and Z = 2 (neotype). The strongest powder X-ray diffraction lines are [dobsin Å (hkl) (Irel)]: 13.10 (001)(100), 6.53 (002)(8), 4.173 (110)(4), 3.517 (112)(5), 2.975 (104, 10$\overline 4 $)(4), 2.676 (211)(5) and 2.520 (12$\bar 2$)(5) (neotype). Thérèsemagnanite is a cobalt analogue of gordaite, NaZn4(SO4)(OH)6Cl·6H2O. These minerals represent the gordaite group, accepted by the IMA CNMNC.

Agmantinite, Ag2MnSnS4, a new mineral with a wurtzite derivative structure from the Uchucchacua polymetallic deposit, Lima Department, Peru

2018 ◽  
Vol 83 (02) ◽  
pp. 233-238
Author(s):  
Frank N. Keutsch ◽  
Dan Topa ◽  
Rie Takagi Fredrickson ◽  
Emil Makovicky ◽  
Werner H. Paar
Keyword(s):  
Crystal Structure ◽  
Empirical Formula ◽  
New Mineral ◽  
Orthorhombic Space Group ◽  
Substitution Pattern ◽  
Calculated Density ◽  
X Ray ◽  
International Mineralogical Association ◽  
Cell Parameters ◽  
Polymetallic Deposit

AbstractAgmantinite, ideally Ag2MnSnS4, is a new mineral from the Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru. It occurs as orange–red crystals up to 100 μm across. Agmantinite is translucent with adamantine lustre and possesses a red streak. It is brittle. Neither fracture nor cleavage were observed. Based on the empirical formula the calculated density is 4.574 g/cm3. On the basis of chemically similar compounds the Mohs hardness is estimated at between 2 to 2½. In plane-polarised light agmantinite is white with red internal reflections. It is weakly bireflectant with no observable pleochroism with red internal reflections. Between crossed polars, agmantinite is weakly anisotropic with reddish brown to greenish grey rotation tints. The reflectances (RminandRmax) for the four standard wavelengths are: 19.7 and 22.0 (470 nm); 20.5 and 23.2 (546 nm); 21.7 and 2.49 (589 nm); and 20.6 and 23.6 (650 nm), respectively.Agmantinite is orthorhombic, space groupP21nm, with unit-cell parameters:a= 6.632(2),b= 6.922(2),c= 8.156(2) Å,V= 374.41(17) Å3,a:b:c0.958:1:1.178 andZ= 2. The crystal structure was refined toR= 0.0575 for 519 reflections withI &gt;2σ(I). Agmantinite is the first known mineral of${M}_{\rm 2}^{\rm I} $MIIMIVS4type that is derived from wurtzite rather than sphalerite by ordered substitution of Zn, analogous to the substitution pattern for deriving stannite from sphalerite. The six strongest X-ray powder-diffraction lines derived from single-crystal X-ray diffraction data [din Å (intensity)] are: 3.51 (s), 3.32 (w), 3.11 (vs), 2.42 (w), 2.04 (m) and 1.88 (m). The empirical formula (based on 8 apfu) is (Ag1.94Cu0.03)Σ1.97(Mn0.98Zn0.05)Σ1.03Sn0.97S4.03.The crystal structure-derived formula is Ag2(Mn0.69Zn0.31)Σ1.00SnS4and the simplified formula is Ag2MnSnS4.The name is for the composition and the new mineral and mineral name have been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2014-083).

Cuyaite, Ca2Mn3+As3+14O24Cl, a new mineral with an arsenite framework from near Cuya, Camarones Valley, Chile.

2020 ◽  
Vol 84 (3) ◽  
pp. 477-484
Author(s):  
Anthony R. Kampf ◽  
Stuart J. Mills ◽  
Barbara Nash ◽  
Maurizio Dini ◽  
Arturo A. Molina Donoso
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Meteoric Water ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
Jahn Teller ◽  
Mohs Hardness ◽  
3D Framework

AbstractCuyaite (IMA2019-126), Ca2Mn3+As3+14O24Cl, is a new arsenite mineral from near Cuya in the Camarones Valley, Arica Province, Chile. It is associated with anhydrite, native arsenic, arsenolite, calcite, claudetite, ferrinatrite, gajardoite-3R, leiteite, magnesiocopiapite, phosphosiderite, pyrite, realgar and talmessite and formed from the oxidation of As-bearing primary phases and alteration by saline fluids derived from evaporating meteoric water under hyperarid conditions. Cuyaite occurs as pale brown thin needles (elongated on [010]), typically in divergent sprays and subparallel intergrowths. The streak is white. Crystals are transparent with adamantine lustre; subparallel intergrowths exhibit silky lustre. The mineral has Mohs hardness of 2½, is brittle, exhibits no cleavage and has irregular fracture. The calculated density is 4.140 g cm–3. Cuyaite is optically biaxial (–), with α = 1.87(1), β = 1.956(calc) and γ = 1.98(1), determined in white light; 2Vmeas = 60(1)°; and orientation: X = b and Y ^ a = 53° in obtuse β. Electron microprobe analyses provided the empirical formula Ca2.03Mn3+0.95(As3+13.66Sb3+0.65)Σ14.31O24Cl0.88. The six strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 4.73(45)(111, $\bar{1}$12), 3.162(100)($\bar{3}$14), 3.035(28)(213), 3.004(37)(204), 2.931(90)($\bar{2}$15, 312) and 2.779(28)(020). Cuyaite is monoclinic, Pn, a = 14.7231(6), b = 5.58709(19), c = 17.4185(12) Å, β = 112.451(8)°, V = 1324.23(14) Å3 and Z = 2. In the crystal structure of cuyaite (R1 = 0.0369 for 2095 I > 2σI reflections), AsO3 pyramids share O corners to form a ‘loose’ 3D framework; Jahn–Teller distorted Mn3+O6 octahedra and CaO8 polyhedra link by edges and corners to form columns; the columns also link by edge- and corner-sharing to the AsO3 pyramids in the framework; Cl occupies channels along [010] in the framework. The Raman spectrum is consistent with the presence of multiple As3+O3 groups.

scholarly journals Grimmite, NiCo<sub>2</sub>S<sub>4</sub>, a new thiospinel from Příbram, Czech Republic

2021 ◽  
Vol 33 (2) ◽  
pp. 175-187
Author(s):  
Pavel Škácha ◽  
Jiří Sejkora ◽  
Jakub Plášil ◽  
Zdeněk Dolníček ◽  
Jana Ulmanová
Keyword(s):  
Czech Republic ◽  
Diffraction Data ◽  
Electron Microprobe ◽  
Coarse Grained ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
Reflected Light ◽  
The Ideal

Abstract. The new mineral grimmite, NiCo2S4, was found in siderite–sphalerite gangue at the dump of shaft no. 9, one of the mines in the abandoned Příbram uranium and base-metal district, central Bohemia, Czech Republic. The new mineral occurs as rare idiomorphic to hypidiomorphic grains up to 200  µm × 70 µm in size or veinlet aggregates. In reflected light, grimmite is creamy grey with a pinkish tint. Pleochroism, polarising colours and internal reflections were not observed. Reflectance values of grimmite in the air (R %) are 42.5 at 470 nm, 45.9 at 546 nm, 47.7 at 589 nm and 50.2 at 650 nm). The empirical formula for grimmite, based on electron-microprobe analyses (n= 13), is Ni1.01(Co1.99Fe0.06Pb0.01Bi0.01)Σ2.07S3.92. The ideal formula is NiCo2S4; requires Ni 19.26, Co 38.67, and S 42.07; and totals 100.00 wt %. According to the single-crystal X-ray diffraction data (Robs=0.0489), grimmite is cubic, Fd–3m, a=9.3933(9), with V=828.81(14) Å3 and Z=8. The calculated density is 4.96 g cm−3. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I)(hkl)] are 3.3210 (75) (220), 2.7116 (7) (222), 2.3483 (81) (400), 1.9174 (27) (422), 1.6605 (100) (440), 1.4852 (11) (620) and 1.3558 (15) (444). Grimmite is named after Johann Grimm (24 June or 24 July 1805 to 26 June 1874), the former director of the Příbram Mining College. The association of sulfides and sulfarsenides was found with grimmite. Essentially non-zoned coarse-grained siderite encloses idiomorphic crystals and/or aggregates of red sphalerite I and zoned skutterudite-group minerals. Skutterudites (skutterudite, niklskutterudite and ferroskutterudite) are usually strongly corroded and replaced by younger phases. Relics of skutterudite are rimmed by nickeline and later on by gersdorffite with rare domains of glaucodot and arsenopyrite, whereas completely leached parts of skutterudite crystals are filled up by quartz containing small isolated grains and aggregates of pyrite, sphalerite II, grimmite, galena, ullmannite, bismuthinite, parkerite and jaipurite, the latter being rarely enclosed in grimmite.

Cámaraite, Ba3NaTi4(Fe2+,Mn)8(Si2O7)4O4(OH,F)7. I. A new Ti-silicate mineral from the Verkhnee Espe Deposit, Akjailyautas Mountains, Kazakhstan

2009 ◽  
Vol 73 (5) ◽  
pp. 847-854 ◽  
Author(s):  
E. Sokolova ◽  
Y. Abdu ◽  
F. C. Hawthorne ◽  
A. V. Stepanov ◽  
G. K. Bekenova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Refractive Indices ◽  
New Mineral ◽  
Silicate Mineral ◽  
Calculated Density ◽  
Triclinic Space Group ◽  
X Ray ◽  
International Mineralogical Association ◽  
Mineralogical Association ◽  
Mohs Hardness

AbstractCámaraite, ideally Ba3NaTi4(Fe2+,Mn)8(Si2O7)4O4(OH,F)7, is a new mineral from the Verkhnee Espe deposit, Akjailyautas Mountains, Kazakhstan. It occurs as intergrowths with bafertisite and jinshajiangite in separate platy crystals up to 8 mm × 15 mm × 2 mm in size, or as star-shaped aggregates of crystals with different orientations. Individual crystals are orange-red to brownish-red, and are platy on {001}. Cámaraite is translucent and has a pale-yellow streak, a vitreous lustre, and does not fluoresce under cathode or ultraviolet light. Cleavage is {001} perfect, no parting was observed, and Mohs hardness is <5; the mineral is brittle. The calculated density is 4.018 g cm-3. In transmitted light, camaraite is strongly pleochroic, X = light brown, Y = reddish-brown, Z = yellow- brown, with Z < X < Y. Cámaraite is biaxial +ve and 2Vmeas. = 93(1)°. All refractive indices are greater than 1.80. Cámaraite is triclinic, space group C, a = 10.678(4) Å, b = 13.744(8) Å, c = 21.40(2) Å, α = 99.28(8)°, β = 92.38(5)°, γ = 90.00(6)°, V = 3096(3) Å3, Z = 4, a:b:c = 0.7761:1:1.5565. The seven strongest lines in the X-ray powder-diffraction pattern are as follows: [d (Å), (I), (hkl)]: 2.63, (100), (401); 2.79, (90), (3, 41, 26, 225); 1.721, (70), (11, 49, 02); 3.39, (50), (24, 223); 3.18, (50), (5, 24); 2.101, (50), (2, 40); 1.578, (50), (1, 2, 61, 40). Chemical analysis by electron microprobe gave: Nb2O5 1.57, SiO2 25.25, TiO2 15.69, ZrO2 0.33, Al2O3 0.13, Fe2O3 2.77, FeO 16.54, MnO 9.46, ZnO 0.12, MgO 0.21, CaO 0.56, BaO 21.11, Na2O 1.41, K2O 0.84, H2O 1.84, F 3.11, less O:F 1.31, total 99.63 wt.%, where the valence state of Fe was determined by Mössbauer spectroscopy [Fe3+/(Fe2+ + Fe3+) = 0.13(8)] and the H2O content was derived by crystal-structure determination. The resulting empirical formula on the basis of 39 anions is Ca0.05)Σ7.78Si7.97O35.89H3.88F3.11. Cámaraite is a Group-II TS-block mineral in the structure hierarchy of Sokolova (2006). The mineral is named camaraite after Fernando Cámaraite (born 1967) of Melilla, Spain, in recognition of his contribution to the fields of mineralogy and crystallography. The new mineral and mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification, International Mineralogical Association (IMA 2009-11).

Windmountainite, □Fe3+2Mg2□2Si8O20(OH)2(H2O)4·4H2O, a new modulated, layered Fe3+-Mg-silicate-hydrate from Wind Mountain, New Mexico: Characterization and origin, with comments on the classification of palygorskite-group minerals

2020 ◽  
Vol 58 (4) ◽  
pp. 477-509
Author(s):  
Derek D. Leung ◽  
Andrew M. McDonald
Keyword(s):  
Crystal Structure ◽  
New Mexico ◽  
Late Stage ◽  
Structure Refinement ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
New Mineral Species

ABSTRACT Windmountainite, ideally □Fe3+2Mg2□2Si8O20(OH)2(H2O)4·4H2O, is a new mineral species and member of the palygorskite group discovered as orange-brown, radiating aggregates that commonly fill vesicles (average 1.5 × 2.5 mm) within a phonolite dike at Wind Mountain, Otero County, New Mexico, USA. The mineral develops as tightly bound bundles (up to 0.02 × 6 mm) of acicular to bladed crystals that are elongate on [001] and flattened on the pinacoid {010}. Associated minerals include albite, aegirine, fluorapophyllite-(K), natrolite, neotocite, and montmorillonite, the last of these being observed to replace primary windmountainite. It has a dull luster, silky in aggregates, is translucent and has an orange-brown streak. It does not fluoresce under short-, medium-, or long-wave ultraviolet radiation. Windmountainite is brittle with a splintery fracture and has two good cleavages (predicted) on {110}, an estimated hardness of 2, a calculated density of 2.51 g/cm3, and a calculated navg of 1.593. A total of n = 30 EMPA (WDS) analyses from six grains yielded an average of (wt.%): Na2O 0.08, MgO 3.47, Al2O3 1.15, SiO2 49.76, Cl 0.07, K2O 0.40, CaO 0.68, TiO2 0.30, MnO 5.64, Fe2O3 20.17, H2O (calc.) 16.59, O=Cl –0.02, total 98.29. The empirical formula [based on Σ(T1, T2, M2, M3) = 12 cations pfu, excluding Ca, K, and Na] is: (□0.78Ca0.12K0.08Na0.02)Σ1.00(Fe3+1.93Al0.04Ti0.02)Σ1.99 (Mg0.81Mn2+0.75Fe3+0.44)Σ2.00□2(Si7.81Al0.17Ti0.01Fe3+0.01)Σ8.00O20[(OH)1.98Cl0.02]Σ2.00[(H2O)3.38(OH)0.62]Σ4.00·4H2O, yielding the simplified formula, □Fe3+2Mg2□2Si8O20(OH)2(H2O)4·4H2O. The predominance of Fe3+ is based on color, results from the crystal-structure refinement, the crystal-chemistry of palygorskite-group minerals, the association with Fe3+-dominant minerals, and considerations regarding the late-stage geochemical evolution of agpaitic rocks. The presence of H2O and OH was determined based on results from the refined crystal structure and Fourier-transform infrared spectroscopy. Windmountainite crystallizes in the space group C2/m with a 13.759(3), b 17.911(4), c 5.274(1) Å, β 106.44(3)°, V 1246.6(1) Å3, and Z = 2. The seven strongest powder X-ray diffraction lines are [d in Å (I), (hkl)]: 10.592 (100) (110), 5.453 (16) (130), 4.484 (19) (040), 4.173 (28) , 3.319 (53) (221, 400), 2.652 (30) , 2.530 (27) . The crystal structure was determined from single-crystal X-ray diffraction data and refined to R = 4.01% and wR2 = 10.70% using data from 902 reflections (Fo &gt; 4σFo). It is based on sheets of inverted double chains of SiO4 tetrahedra that sandwich ribbons of Mφ6 octahedra (φ = O, OH, H2O, Cl), giving rise to large channels (∼6.5 × 9 Å) that are occupied by loosely held H2O groups. A modified classification of the palygorskite group [general crystal-chemical formula M1M22M32M42T14T24O20(OH)2(H2O,OH)4·W] is proposed based on the occupants of the four M sites. Within this scheme, windmountainite is the □-Fe3+-Mg-□ member. The palygorskite group includes six members: palygorskite (monoclinic and orthorhombic polytypes), yofortierite, tuperssuatsiaite, raite, windhoekite, and windmountainite. Windmountainite is considered to have formed from late-stage fluids that were alkaline, oxidized, and rich in both Fe3+ and H2O; high aH2O conditions are reflective of abundant, hydrated feldspathoids (natrolite and analcime) forming as primary rock-forming minerals in the phonolite at Wind Mountain.

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