| 1. |
- Chukanov, Nikita V., et al.
(författare)
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Långbanshyttanite, a new low-temperature arsenate mineral with a novel structure from Långban, Sweden
- 2011
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Ingår i: European journal of mineralogy. - : Schweizerbart. - 0935-1221 .- 1617-4011. ; 23:4, s. 675-681
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Tidskriftsartikel (refereegranskat)abstract
- The new mineral långbanshyttanite was discovered in a specimen from the Långban mine (59.86 degrees N, 14.27 degrees E), Filipstad district, Varmland County, Bergslagen ore province, Sweden. Associated minerals are calcite, Mn-bearing phlogopite, spinels of the jacobsite-magnetite series, antigorite and trigonite. The mineral is named after the old name of the mine, smelter and mining village: Långbanshyttan. Långbanshyttanite is transparent, colourless. It occurs in late-stage fractures or corroded pockets, forming soft, radial and random aggregates (up to 1 mm) of acicular crystals up to 5 x 20 x 400 mu m. D(calc) is 3.951 g/cm(3). The new mineral is biaxial (+), alpha = 1.700(5), beta = 1.741(5), gamma = 1.792(5), 2V (meas.) approximate to 90 degrees, 2V (calc.) = 86 degrees. Dispersion is strong, r < v. The IR spectrum is given. The chemical composition is (electron microprobe, mean of five analyses, wt%): PbO 44.71, MgO 3.79, MnO 13.34, FeO 1.89, P(2)O(5) 0.65, As(2)O(5) 22.90, H(2)O (determined by gas chromatographic analysis of the products of ignition at 1200 degrees C) 14.4; total 101.68. The empirical formula based on 18 O atoms is: Pb(1.97)Mn(1.85)Mg(0.93)Fe(0.26)(AsO(4))(1.96)(PO(4))(0.09)(OH)(3.87)cen ter dot 5.93H(2)O. The simplified formula is: Pb(2)Mn(2)Mg(AsO(4))(2)(OH)(4)center dot 6H(2)O. Single-crystal diffraction data obtained using synchrotron radiation indicate that långbanshyttanite is triclinic, P<(1)over bar>, a = 5.0528(10), b = 5.7671(6), c = 14.617(3) angstrom, alpha = 85.656(14), beta = 82.029(17), gamma = 88.728(13)degrees, V = 420.6(2) angstrom(3), Z = 1, and is a representative of a new structure type. In the structure, edge-sharing MnO(2)(OH)(4) octahedra form zig-zag columns that are linked by isolated AsO(4) tetrahedra. Pb cations having six-fold coordination are located between the AsO(4) tetrahedra. Isolated Mg(H(2)O)(6) octahedra are located in the inter-block space. The strongest lines of the powder diffraction pattern [d, angstrom (I,%) (hkl)] are: 14.48 (100) (001), 7.21 (43) (002), 4.969 (34) (100, 101), 4.798 (28) (003), 3.571 (54) (112, 1-1-1, 01-3, 11-1), 2.857 (45) (020, 021, 114), 2.800 (34) (11-3). Parts of the holotype specimen are deposited in the Fersman Mineralogical Museum of Russian Academy of Sciences, Moscow, Russia, with the registration number 4032/1 and in the collections of the Swedish Museum of Natural History, Stockholm, Sweden, under catalogue number NRM 20100076.
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| 2. |
- Gorelova, Liudmila, et al.
(författare)
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Edge-sharing BO4 tetrahedra and penta-coordinated silicon in the high-pressure modification of NaBSi3O8
- 2022
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Ingår i: Inorganic Chemistry Frontiers. - : ROYAL SOC CHEMISTRY. - 2052-1545 .- 2052-1553. ; 9:8, s. 1735-1742
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Tidskriftsartikel (refereegranskat)abstract
- The high-pressure behavior of the borosilicate reedmergnerite NaBSi3O8 has been studied using in situ single-crystal X-ray diffraction and Raman spectroscopy up to 35 GPa. The crystal structure of NaBSi3O8 contracts homogeneously upon compression up to 12 GPa, while at higher pressures it undergoes two phase transitions. Above 16 GPa the unit-cell volume is doubled, whereas the coordination numbers of all cations and the structural topology are preserved. Above 25 GPa the crystal structure of NaBSi3O8 contains extremely rare dimers of edge-sharing BO4 tetrahedra and earlier unknown Si2O5 groups consisting of edge-sharing SiO5 square pyramids. The structural model was corroborated by DFT calculations. This HP modification results in the first example of a borosilicate compound with edge-sharing BO4 tetrahedra.
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| 3. |
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| 4. |
- Siidra, Oleg, I, et al.
(författare)
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Grootfonteinite, Pb3O(CO3)(2), a new mineral species from the Kombat Mine, Namibia, merotypically related to hydrocerussite
- 2018
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Ingår i: European journal of mineralogy. - : E SCHWEIZERBARTSCHE VERLAGSBUCHHANDLUNG. - 0935-1221 .- 1617-4011. ; 30:2, s. 383-391
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Tidskriftsartikel (refereegranskat)abstract
- Grootfonteinite, Pb3O(CO3)(2), is a new Pb oxycarbonate found in a mineralogically complex, banded assemblage from the Mn (-Fe) oxide ore unit of the Kombat mine. Grootfonteinite is named after the locality in the Grootfontein district. The mineral forms platy grains up to 1 mm across and up to 0.2 mm thick included in and intergrown with massive cerussite. Grootfonteinite is colourless, with white streak and adamantine lustre. It is brittle with perfect cleavage on (0 0 1). The density calculated using the empirical formula H0.345Na0.275Ca0.045Pb2.645C2O7 is 6.856 g.cm(-3). The strongest five reflections in the X-ray powder-diffraction pattern [(d in angstrom)-(Intensity)-(hkl)] are: 4.586-25-0 1 0, 3.244-100-0 1 3, 2.652-30-1 1 0, 2.294-21-0 2 0, 2.053-39-0 2 3. Grootfonteinite crystallizes in space group P6(3)/mmc (No. 194), a = 5.303(1), c = 13.770(3) angstrom, v= 335.3(1) angstrom(3), Z= 2. The crystal structure of grootfonteinite is formed by layered blocks which consist of sheets with composition [PbCO3] and (ideally) [PbO], the stacking of which can be described as center dot center dot center dot-[PbCO3]-[PbO]-[PbCO3]-center dot center dot center dot The composition of the resulting electroneutral 2D block is {[Pb-2(CO3)(2)][(Pb0.7Na0.3)(O-0.7(OH)(0.3))]}(0). The stereochemically active 6S(2) lone electron pairs of the two Pb atoms are located in between the blocks, resembling the classical case of the structure of litharge. Grootfonteinite is structurally related to hydrocerussite, abellaite, and plumbonacrite. A characteristic structural feature of all these minerals is the presence of [PbCO3](0) sheets in the upper and lower parts of invariably electroneutral 2D blocks, the middle part being variable. The topology of 2D blocks in the crystal structure of grootfonteinite can be considered as intermediate between those of abellaite and hydrocerussite. These three minerals can be considered to form a merotype family. Other members of this family can be hypothesized which differ in the nature of the interleaved sheets.
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| 5. |
- Zhitova, Elena S., et al.
(författare)
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Erssonite, CaMg7Fe23+(OH)(18)(SO4)(2)center dot 12H(2)O, a new hydrotalcite-supergroup mineral from Långban, Sweden
- 2021
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Ingår i: Mineralogical magazine. - : Mineralogical Society. - 0026-461X .- 1471-8022. ; 85:5, s. 817-826
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Tidskriftsartikel (refereegranskat)abstract
- The new wermlandite-group mineral erssonite, ideally CaMg7Fe23+(OH)(18)(SO4)(2)center dot 12H(2)O (or [Mg7Fe23+(OH)(18)][Ca(SO4)(2)].12H(2)O), was discovered in a late-stage, low-temperature assemblage in cavities of a magnetite-bearing dolomitic rock from the Langban deposit, Varmland county, Bergslagen ore province, Sweden. The associated minerals are dolomite, calcite, members of the magnetite-magnesioferrite solid-solution series, phlogopite, chrysotile, pyroaurite and norbergite. Erssonite has a vitreous lustre and forms colourless, platy hexagonal crystals flattened on [0001], up to 0.5 mm across and up to 10 mu m thick, occurring mainly as aggregates in cavities of dolomitic rock. Erssonite is malleable; separate crystals are flexible and non-elastic, with a perfect, mica-like cleavage on {0001}. The calculated density is equal to 2.02 g.cm(-3). Raman spectroscopy shows the presence of typical bands for S-O bonds attributed to intercalated SO42- anions and structural OH- anions together with the absence of C-O bonds, attributed to carbonate anions. The chemical composition is (wt.%, electron microprobe, H2O content is calculated from structure data): MgO 28.67, CaO 2.76, Al2O3 0.23, Cr2O3 0.23, Fe2O3 16.00, SiO2 0.48, SO3 14.80, H2O 35.58, total 98.75. The empirical formula based on 38 O atoms is H41.48Ca0.52Mg7.47Fe2.113+Al0.05Cr0.03S1.94Si0.08O38. The ideal formula is CaMg7Fe23+(OH)(18)(SO4)(2).12H(2)O or {Mg7Fe23+(OH)(18)}{[Ca(H2O)(6)] (SO4)(2)(H2O)(6)}. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.093. Erssonite is trigonal, P (3) over bar c1, with a = 9.3550(6), c = 22.5462(14) angstrom, V = 1708.8(2) angstrom(3) and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, angstrom (I, %)(hkl)] are: 11.22 (90)(002), 5.63 (64)(004), 4.670 (100)(110, 104, 014), 2.626 (64)(032, 302), 2.435 (66)(034, 304) and 1.951 (45)(038, 308). The mineral is named in honour of the Swedish amateur mineralogist Dr. Anders Ersson (b. 1971).
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