Crystal structure and crystal chemistry of fluoro-potassic-magnesio-arfvedsonite from Monte Metocha, Xixano region, Mozambique, and discussion of the holotype from Quebec, Canada

2010 ◽  
Vol 74 (6) ◽  
pp. 951-960 ◽  
Author(s):  
R. Oberti ◽  
M. Boiocchi ◽  
F. C. Hawthorne ◽  
P. Robinson
Keyword(s):  
Polarized Light ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Amphibole Composition ◽  
Fine Grained ◽  
Holotype Specimen ◽  
Cell Dimensions ◽  
Mohs Hardness ◽  
Crystallization Conditions ◽  
Unit Cell Dimensions

AbstractFluoro-potassic-magnesio-arfvedsonite, ideally AKBNa2c(Mg4Fe3+)TSi8O22wF2, has been found in a dyke ∼25 km southwest of Monte Metocha, Xixano region, northeastern Mozambique. Fluoro-potassic-magnesio-arfvedsonite and low sanidine form a fine-grained mafic, ultrapotassic, peralkaline igneous rock without visible phenocrysts. The amphibole is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage and no observable parting, and has a calculated density of 3.174 gcm−3. In plane-polarized light, it is pleochroic, X= pale grey-green, Y = blue-green, Z = pale grey; X ^ c = 23.6° (in β obtuse), Y ‖ b, Z ^ c = 66.4° (in β acute). Fluoro-potassic-magnesio-arfvedsonite is biaxial negative, α = 1.652(2), β = 1.658(2), γ = 1.660(2); 2Vobs = 22.5(7)°, 2Vcalc = 30.2°. The unit-cell dimensions are a = 9.9591(4), b = 17.9529(7), c = 5.2867(2) Å, β = 104.340(1)°, V = 919.73(10) Å3, Z = 2. The nine strongest X-ray diffraction lines in the experimental powder pattern are: [d in Å(I)(hkl)]: 2.716(100)(151), 3.410(70)(131), 8.475(50)(110), 3.178(50)(310), 3.309(30)(240), 2.762(20)(31), 2.549(20)(260), 2.351(10)(51), 2.269(10)(331). Electron microprobe analysis gave: SiO2 54.25, A12O3 0.03, TiO2 1.08, FeO 6.69, Fe2O3 8.07, MgO 13.99, MnO 0.32, ZnO 0.05, CaO 1.16, Na2O 6.33, K2O 5.20, F 2.20, H2Ocalc 0.74, sum 99.18 wt.%. The formula unit, calculated on the basis of 24 (O,OH,F) with (OH+F) = 2−(2 Ti), is AKa0.98B(Na1.18Ca0.18)∑1.99C(Mg3.07Fe0.832+Mn0.04Al0.01Fe0.903+Ti0.12Zn0.01)∑=4.98TSi8O22W[Fi.o3(OH)0.73O0.24]∑2.00 and confirms the usual pattern of cation order in the amphibole structure. The presence of a significant oxo component (locally balanced by Ti at the M(1) site) is related to the crystallization conditions. The presence of Fe3+ at the T sites, originally suggested for the holotype specimen, is discounted for this amphibole composition.

scholarly journals Lead-tellurium oxysalts from Otto Mountain near Baker, California, USA: XII. Andychristyite, PbCu2+Te6+O5(H2O), a new mineral with hcp stair-step layers

2016 ◽  
Vol 80 (6) ◽  
pp. 1055-1065 ◽  
Author(s):  
Anthony R. Kampf ◽  
Mark A. Cooper ◽  
Stuart J. Mills ◽  
Robert M. Housley ◽  
George R. Rossman
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Quartz Veins ◽  
Bluish Green ◽  
Cell Dimensions ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Unit Cell Dimensions

AbstractAndychristyite, PbCu2+Te6+O5(H2O), is a new tellurate mineral from Otto Mountain near Baker, California, USA. It occurs in vugs in quartz in association with timroseite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Andychristyite is triclinic, space group P1̄, with unit-cell dimensions a = 5.322(3), b = 7.098(4), c = 7.511 (4) Å, α = 83.486(7), β = 76.279(5), γ = 70.742(5)°, V = 260.0(2) Å3 and Z = 2. It forms as small tabular crystals up to ∼50 μm across, in sub-parallel aggregates. The colour is bluish green and the streak is very pale bluish green. Crystals are transparent with adamantine lustre. The Mohs hardness is estimated at between 2 and 3. Andychristyite is brittle with an irregular fracture and one perfect cleavage on {001}. The calculated density based on the empirical formula is 6.304 g/cm3. The mineral is optically biaxial, with large 2V, strong dispersion, and moderate very pale blue-green to medium blue-green pleochroism. The electron microprobe analyses (average of five) provided: PbO 43.21, CuO 15.38, TeO3 35.29, H2O 3.49 (structure), total 97.37 wt.%. The empirical formula (based on 6 O apfu) is: Pb0.98Cu2+0.98Te6+1.02O6H 1.96. The Raman spectrum exhibits prominent features consistent with the mineral being a tellurate, as well as an OH stretching feature confirming a hydrous component. The eight strongest powder X-ray diffraction lines are [dobs in Å(I)(hkl)]: 6.71(16)(010), 4.76(17)(110), 3.274(100)(120,102,012), 2.641(27)(102, 211, 112), 2.434(23)(multiple), 1.6736(17)(multiple), 1.5882(21)(multiple) and 1.5133(15)(multiple). The crystal structure of andychristyite (R1 = 0.0165 for 1511 reflections with Fo > 4σF) consists of stair-step-like hcp polyhedral layers of Te6+O6 and Cu2+O6 octahedra parallel to {001}, which are linked in the [001] direction by bonds to interlayer Pb atoms. The structures of eckhardite, bairdite, timroseite and paratimroseite also contain stair-step-like hcp polyhedral layers.

scholarly journals Kyawthuite, Bi3+Sb5+O4, a new gem mineral from Mogok, Burma (Myanmar)

2017 ◽  
Vol 81 (3) ◽  
pp. 477-484 ◽  
Author(s):  
Anthony R. Kampf ◽  
George R. Rossman ◽  
Chi Ma ◽  
Peter A. Williams
Keyword(s):  
Monoclinic Space Group ◽  
Optical Orientation ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Electron Pairs ◽  
X Ray ◽  
Conchoidal Fracture ◽  
Cell Dimensions ◽  
Mohs Hardness ◽  
Unit Cell Dimensions

AbstractKyawthuite, Bi3+Sb5+O4, is a new gem mineral found as a waterworn crystal in alluvium at Chaung-gyi-ah-le-ywa in the Chaung-gyi valley, near Mogok, Burma (Myanmar). Its description is based upon a single sample, which was faceted into a 1.61-carat gem.The composition suggests that the mineral formed in a pegmatite. Kyawthuite is monoclinic, space group I2/c, with unit cell dimensions a = 5.4624(4), b = 4.88519(17), c = 11.8520(8) Å, β = 101.195(7)°, V = 310.25(3) Å3and Z = 4. The colour is reddish orange and the streak is white. It is transparent with adamantine lustre. The Mohs hardness is 5½. Kyawthuite is brittle with a conchoidal fracture and three cleavages: {001} perfect, {110} and {110} good. The measured density is 8.256(5) g cm–3and the calculated density is 8.127 g cm–3. The mineral is optically biaxial with 2V = 90(2)°. The predicted indices of refraction are α = 2.194, β = 2.268, γ = 2.350. Pleochroism is imperceptible and the optical orientation is X = b; Y≈ c; Z ≈ a. Electron microprobe analyses, provided the empirical formula (Bi0.823+Sb0.183+)∑1.00(Sb0.995+Ta0.015+)∑1.00O4. The Raman spectrumis similar to that of synthetic Bi3+Sb5+O4. The infrared spectrum shows a trace amount of OH/H2O. The eight strongest powder X-ray diffraction lines are [dobs in Å(I)(hkl)]: 3.266(100)(112), 2.900(66)(112), 2.678(24)(200), 2.437(22)(020,114), 1.8663(21)(024), 1.8026(43)(116,220,204), 1.6264(23)(224,116) and 1.5288(28)(312,132). In the crystal structure of kyawthuite (R1 = 0.0269 for 593 reflections with Fo > 4σF), Sb5+O6 octahedrashare corners to form chequerboard-like sheets parallel to {001}. Atoms of Bi3+, located above and below the open squares in the sheets, form bonds to the O atoms in the sheets, thereby linking adjacent sheets into a framework. The Bi3+ atom is in lopsided 8 coordination,typical of a cation with stereoactive lone electron pairs. Kyawthuite is isostructural with synthetic β-Sb2O4 and clinocervantite (natural β-Sb2O4).

Penberthycroftite, [Al6(AsO4)3(OH)9(H2O)5]·8H2O, a second new hydrated aluminium arsenate mineral from the Penberthy Croft mine, St. Hilary, Cornwall, UK

2016 ◽  
Vol 80 (7) ◽  
pp. 1149-1160 ◽  
Author(s):  
I. E. Grey ◽  
J. Betterton ◽  
A. R. Kampf ◽  
C. M. Macrae ◽  
F. L. Shanks ◽  
...  
Keyword(s):  
Layer Structure ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Single Crystal Diffraction ◽  
Calculated Density ◽  
Metal Atoms ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Hydrated Aluminium ◽  
The Ideal

AbstractPenberthycroftite, ideally [Al6(AsO4)3(OH)9(H2O)5]·8H2O, is a new secondary aluminium arsenate mineral from the Penberthy Croft mine, St. Hilary, Cornwall, England, UK. It occurs as tufts of white, ultrathin (sub-micrometre) rectangular laths, with lateral dimensions generally < 20 μm. The laths are flattened on {010} and elongated on [100]. The mineral is associated with arsenopyrite, bettertonite, bulachite, cassiterite, chalcopyrite, chamosite, goethite, liskeardite, pharmacoalumite–pharmacosiderite and quartz. Penberthycroftite is translucent with a white streak and a vitreous to pearly lustre. The calculated density is 2.18 g/cm3. Optically, only the lower and upper refractive indices could be measured, 1.520(1) and 1.532(1) respectively. No pleochroism was observed. Electron microprobe analyses (average of 14) with H2O obtained from thermogravimetric analysis and analyses normalized to 100% gave Al2O3 = 31.3, Fe2O3 = 0.35, As2O5 = 34.1, SO3 = 2.15 and H2O = 32.1. The empirical formula, based on nine metal atoms and 26 framework anions is [Al5.96Fe0.04(As0.97Al0.03O4)3(SO4)0.26(OH)8.30(H2O)5.44](H2O)7.8, corresponding to the ideal formula [Al6(AsO4)3(OH)9(H2O)5]·8H2O. Penberthycroftite is monoclinic, space group P21/c with unit-cell dimensions (100 K): a = 7.753(2) Å, b = 24.679(5) Å, c = 15.679(3) Å and β = 94.19(3)°. The strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I) (hkl)] 13.264(46) (011); 12.402(16)(020); 9.732(100)(021); 7.420(28)(110); 5.670(8)(130); 5.423(6)(1̄31). The structure of penberthycroftite was solved using synchrotron single-crystal diffraction data and refined to wRobs = 0.059 for 1639 observed (I> 3σ(I)) reflections. Penberthycroftite has a heteropolyhedral layer structure, with the layers parallel to {010}. The layers are strongly undulating and their stacking produces large channels along [100] that are filled with water molecules. The layers are identical to those in bettertonite, but they are displaced relative to one another along [001] and [010] such that the interlayer volume is decreased markedly (by ∼10%)relative to that in bettertonite, with a corresponding reduction in the interlayer water content from 11 H2O per formula unit (pfu) in bettertonite to 8 H2O pfu in penberthycroftite.

Bettertonite, [Al6(AsO4)3(OH)9(H2O)5]·11H2O, a new mineral from the Penberthy Croft mine, St. Hilary, Cornwall, UK, with a structure based on polyoxometalate clusters

2015 ◽  
Vol 79 (7) ◽  
pp. 1849-1858 ◽  
Author(s):  
I.E. Grey ◽  
A.R. Kampf ◽  
J.R. Price ◽  
C.M. Macrae
Keyword(s):  
Layer Structure ◽  
New Mineral ◽  
Water Molecules ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Hexagonal Ring ◽  
Metal Atoms ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractBettertonite, ideally [Al6(AsO4)3(OH)9(H2O)5]·11H2O, is a new mineral from the Penberthy Croft mine, St. Hilary, Cornwall, England, UK. It occurs as tufts of white, ultrathin (sub-micrometre) rectangular laths, with lateral dimensions generally <20 μm. The laths are flattened on {010} and exhibit the forms {010}, {100} and {001}. The mineral is associated closely with arsenopyrite, chamosite, liskeardite, pharmacoalumite, pharmacosiderite and quartz. Bettertonite is translucent with a white streak and a vitreous to pearly, somewhat silky lustre. The calculated density is 2.02 g/cm3. Optically, bettertonite is biaxial positive with α = 1.511(1), β = 1.517(1), γ = 1.523(1) (in white light). The optical orientation is X = c, Y= b, Z = a. Pleochroism was not observed. Electron microprobe analyses (average of 4) with H2O calculated on structural grounds and analyses normalized to 100% gave Al2O3 = 29.5, Fe2O3 = 2.0, As2O5= 30.1, SO3 = 1.8, Cl = 0.5, H2O = 36.2. The empirical formula, based on 9 metal atoms is Al5.86Fe0.26(AsO4)2.65(SO4)0.23(OH)9.82Cl0.13(H2O)15.5. Bettertoniteis monoclinic, space group P21/c with unit-cell dimensions (100 K): a = 7.773(2), b = 26.991(5), c = 15.867(3) Å, β = 94.22(3)°. The strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I)(hkl)] 13.648(100)(011); 13.505(50) (020); 7.805(50)(031); 7.461(30)(110); 5.880(20)(130); 3.589(20)(02); 2.857(14)(182). The structure of bettertonite was solved and refined to R1 = 0.083 for 2164 observed (I > 2σ(I)) reflections to a resolutionof 1 Å. Bettertonite has a heteropolyhedral layer structure, with the layers parallel to (010). The layers are strongly undulating and their stacking produces large channels along [100] that are filled with water molecules. The basic building block in the layers is a hexagonal ring ofedge-shared octahedra with an AsO4 tetrahedron attached to one side of the ring by corner-sharing. These polyoxometalate clusters, of composition [AsAl6O11(OH)9(H2O)5]8–, are interconnected along [100] and [001]by corner-sharing with other AsO4 tetrahedra.

Crystal structure analysis of ebastine [4-(4-benzhydryloxy-1-piperidyl)-1-(4-tert-butylphenyl) butan-1-one]: an oral histamine antagonist

2015 ◽  
Vol 48 (4) ◽  
pp. 1299-1301 ◽  
Author(s):  
Ranjana Sharma ◽  
Dixit Prasher ◽  
R. K. Tiwari
Keyword(s):  
Bond Length ◽  
Chair Conformation ◽  
Crystal Structure Analysis ◽  
Piperidine Ring ◽  
X Ray Diffraction ◽  
H1 Receptor ◽  
Calculated Density ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Good Agreement

Ebastine belongs to the category of second-generation non-sedating H1 receptor antagonists and is chiefly used for the treatment of allergic rhinitis and chronic urticaria. The present paper reports findings on the crystal and molecular structure of ebastine, employing the technique of single-crystal X-ray diffraction. Ebastine crystallizes in the monoclinicP21/cspace group with unit-cell dimensionsa= 16.5890 (12),b= 10.9575 (8),c= 16.6795 (11) Å, β = 113.623 (2)°,V= 2777.8 (3) Å3,Z= 4 and calculated density amounting to 1.123 Mg m−3. The structure factor value was observed 1016 and finalR= 0.0496 for 4360 unique reflections. The piperidine ring in the ebastine molecule was found to exist in a chair conformation, and the C—N bond length was 1.459 (3) Å, thereby showing good agreement with the standard C—N bond length of 1.472 Å.

Crystallization and preliminary X-ray diffraction studies of blasticidin S deaminase from Aspergillus terreus

1999 ◽  
Vol 55 (2) ◽  
pp. 547-548 ◽  
Author(s):  
Masayoshi Nakasako ◽  
Makoto Kimura ◽  
Isamu Yamaguchi
Keyword(s):  
Diffraction Data ◽  
Aspergillus Terreus ◽  
Crystal Structure Analysis ◽  
Thin Plates ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Cell Dimensions ◽  
Crystallization Conditions ◽  
Blasticidin S ◽  
Unit Cell Dimensions

Blasticidin S deaminase from Aspergillus terreus was crystallized with polyethylene glycol 8000. Two types of crystals were grown under the same crystallization conditions. One type grew as thin plates, while the other had a rhombic shape. The rhombic shaped crystal was suitable for high-resolution crystal structure analysis. Precession photographs and diffraction data showed that the crystal belonged to orthorhombic space group P212121, with unit-cell dimensions a = 70.33, b = 146.56 and c = 56.48 Å. The calculated Vm value was acceptable when a tetramer of the enzyme was contained in an asymmetric unit. Preliminary diffraction data were collected to a resolution of 2.0 Å with good statistics.

scholarly journals Fluorarrojadite-(BaNa), BaNa4CaFe13Al(PO4)11(PO3OH)F2, a new member of the arrojadite group from Gemerská Poloma, Slovakia

2018 ◽  
Vol 82 (4) ◽  
pp. 863-876 ◽  
Author(s):  
Martin Števko ◽  
Jiří Sejkora ◽  
Pavel Uher ◽  
Fernando Cámara ◽  
Radek Škoda ◽  
...  
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Yellow Colour ◽  
Fine Grained ◽  
Quartz Veins ◽  
Mohs Hardness ◽  
Dominant Cation

ABSTRACTThe new mineral fluorarrojadite-(BaNa), ideally BaNa4CaFe13Al(PO4)11(PO3OH)F2 was found on the dump of Elisabeth adit near Gemerská Poloma, Slovakia. It occurs in hydrothermal quartz veins intersecting highly fractionated, topaz–zinnwaldite S-type leucogranite. Fluorarrojadite-(BaNa) is associated with fluorapatite, ‘fluordickinsonite-(BaNa)’, triplite, viitaniemiite and minor amounts of other minerals. It forms fine-grained irregular aggregates up to 4 cm x 2 cm, which consist of individual anhedral grains up to 0.01 mm in size. It has a yellowish-brown to greenish-yellow colour, very pale yellow streak and a vitreous to greasy lustre. Mohs hardness is ~4½ to 5. The fracture is irregular and the tenacity is brittle. The measured density is 3.61(2) g cm–3 and calculated density is 3.650 g cm–3. Fluorarrojadite-(BaNa) is biaxial (+) and nonpleochroic. The calculated refractive index based on empirical formula is 1.674. The empirical formula (based on 47 O and 3 (OH + F) apfu) is A1(Ba0.65K0.35)Σ1.00 A2Na0.35 B1(Na0.54Fe0.46)Σ1.00 B2Na0.54Ca(Ca0.74Sr0.20Pb0.02Ba0.04)Σ1.00Na2 Na3Na0.46 M(Fe7.16Mn5.17Li0.37Mg0.12Sc0.08Zn0.06Ga0.02Ti0.02)Σ13.00 Al1.02P11O44PO3.46(OH)0.54 W(F1.54OH0.46). Fluorarrojadite-(BaNa) is monoclinic, space group Cc, a = 16.563(1) Å, b = 10.0476(6) Å, c = 24.669(1) Å, β = 105.452(4)°, V = 3957.5(4) Å3 and Z = 4. The seven strongest reflections in the powder X-ray diffraction pattern are [dobs in Å, (I), hkl]: 3.412, (21), 116; 3.224, (37), 206; 3.040, (100), 42$\bar 4$; 2.8499, (22), 33$\bar 3$; 2.7135, (56), 226; 2.5563, (33), 028 and 424; 2.5117, (23), 040. The new mineral is named according to the nomenclature scheme of arrojadite-group minerals, approved by the IMA CNMNC. In fluorarrojadite-(BaNa), Fe2+ is a dominant cation at the M site (so the root-name is arrojadite) and two suffixes are added to the root-name according to the dominant cation of the dominant valence state at the A1 (Ba2+) and B1 sites (Na+). A prefix fluor is added to the root-name as F– is dominant over (OH)– at the W site.

Fluor-tsilaisite, NaMn3Al6(Si6O18)(BO3)3(OH)3F, a new tourmaline from San Piero in Campo (Elba, Italy) and new data on tsilaisitic tourmaline from the holotype specimen locality

2015 ◽  
Vol 79 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Ferdinando Bosi ◽  
Giovanni B. Andreozzi ◽  
Giovanna Agrosi ◽  
Eugenio Scandale
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
Crystal Chemical Analysis ◽  
Calculated Density ◽  
Conchoidal Fracture ◽  
Holotype Specimen ◽  
Greenish Yellow ◽  
Pegmatite Body ◽  
Mohs Hardness ◽  
Mn Content

AbstractFluor-tsilaisite, NaMn3Al6(Si6O18)(BO3)3(OH)3F, is a new mineral of the tourmaline supergroup. It occurs in an aplitic dyke of a LCT-type pegmatite body from Grotta d'Oggi, San Piero in Campo, Elba Island, Italy, in association with quartz, K-feldspar, plagioclase, elbaite, schorl, fluor-elbaite and tsilaisite. Crystals are greenish yellow with a vitreous lustre, sub-conchoidal fracture and white streak. Fluor-tsilaisite has a Mohs hardness of ∼7 and a calculated density of 3.134 g/cm3. In plane-polarized light, fluor-tsilaisite is pleochroic (O = pale greenish yellow and E = very pale greenish yellow), uniaxial negative. Fluor-tsilaisite is rhombohedral, space group R3m, a = 15.9398(6), c = 7.1363(3) Å, V = 1570.25(11) Å3, Z = 3. The crystal structure of fluor-tsilaisite was refined to R1 = 3.36% using 3496 unique reflections collected with MoKα X-ray intensity data. Crystal-chemical analysis resulted in the empirical formula: X(Na0.69〈0.29Ca0.02)Σ1.00Y(Mn2+1.29Al1.21Li0.56Ti0.03)Σ6.00ZAl6T(Si5.98Al0.03)Σ6.00B2.92O27V(OH)3W[F0.39(OH)0.25O0.36]Σ1.00.Comparisons were performed between fluor-tsilaisite and a tsilaisitic tourmaline from the same locality as the holotype specimen. This latter tourmaline sample was selected for this study due to its remarkable composition (MnO = 11.63 wt.%), the largest Mn content found in tourmaline so far.Fluor-tsilaisite is related to tsilaisite through the substitution WF ↔ W(OH) and with fluor-elbaite through the substitution Y(Al + Li) ↔ 2YMn2+, and appears to be a stepwise intermediate during tourmaline evolution from tsilaisite to fluor-elbaite.

Dalnegroite, Tl5–xPb2x(As,Sb)2l–xS34, a new thallium sulphosalt from Lengenbach quarry, Binntal, Switzerland

2009 ◽  
Vol 73 (6) ◽  
pp. 1027-1032 ◽  
Author(s):  
F. Nestola ◽  
A. Guastoni ◽  
L. Bindi ◽  
L. Secco
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Concentrations ◽  
Reflected Light ◽  
Mohs Hardness ◽  
The Mean ◽  
The University ◽  
Probable Space

AbstractDalnegroite, ideally Tl4Pb2(As12Sb8)Σ20S34, is a new mineral from Lengenbach, Binntal, Switzerland. It occurs as anhedral to subhedral grains up to 200 μm across, closely associated with realgar, pyrite, Sb-rich seligmanite in a gangue of dolomite. Dalnegroite is opaque with a submetallic lustre and shows a brownish-red streak. It is brittle; the Vickers hardness (VHN25) is 87 kg mm-2(range: 69—101) (Mohs hardness ∼3—3½). In reflected light, dalnegroite is highly bireflectant and weakly pleochroic, from white to a slightly greenish-grey. In cross-polarized light, it is highly anisotropic with bluish to green rotation tints and red internal reflections.According to chemical and X-ray diffraction data, dalnegroite appears to be isotypic with chabournéite, Tl5-xPb2x(Sb,As)21-xS34. It is triclinic, probable space groupP1, witha= 16.217(7) Å,b= 42.544(9) Å,c= 8.557(4) Å, α = 95.72(4)°, β = 90.25(4)°, γ = 96.78(4)°,V= 5832(4) Å3,Z= 4.The nine strongest powder-diffraction lines [d(Å) (I/I0) (hkl)] are: 3.927 (100) (10 0); 3.775 (45) (22); 3.685 (45) (60); 3.620 (50) (440); 3.124 (50) (2); 2.929 (60) (42); 2.850 (70) (42); 2.579 (45) (02); 2.097 (60) (024). The mean of 11 electron microprobe analyses gave elemental concentrations as follows: Pb 10.09(1) wt.%, Tl 20.36(1), Sb 23.95(1), As 21.33(8), S 26.16(8), totalling 101.95 wt.%, corresponding to Tl4.15Pb2.03(As11.86Sb8.20)S34. The new mineral is named for Alberto Dal Negro, Professor in Mineralogy and Crystallography at the University of Padova since 1976.

Crystallization and preliminary X-ray diffraction studies of human catalase

1999 ◽  
Vol 55 (9) ◽  
pp. 1614-1615 ◽  
Author(s):  
R. A. P. Nagem ◽  
E. A. L. Martins ◽  
V. M. Gonçalves ◽  
R. Aparício ◽  
I. Polikarpov
Keyword(s):  
Search Model ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
Beef Liver ◽  
X Ray ◽  
Diffusion Technique ◽  
Cell Dimensions ◽  
Synchrotron Radiation Diffraction ◽  
Replacement Solution ◽  
Unit Cell Dimensions

The enzyme catalase (H2O2–H2O2 oxidoreductase; E.C. 11.1.6) was purified from haemolysate of human placenta and crystallized using the vapour-diffusion technique. Synchrotron-radiation diffraction data have been collected to 1.76 Å resolution. The enzyme crystallized in the space group P212121, with unit-cell dimensions a = 83.6, b = 139.4, c = 227.5 Å. A molecular-replacement solution of the structure has been obtained using beef liver catalase (PDB code 4blc) as a search model.

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