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The cobalt carbonate hydroxide Co2CO3(OH)2 is a technologically important solid which is used as a precursor for the synthesis of cobalt oxides in a wide range of applications. It also has relevance as a potential immobilizer of the toxic element cobalt in the natural environment, but its detailed crystal structure is so far unknown. The structure of Co2CO3(OH)2 has now been investigated using density functional theory (DFT) simulations and powder X-ray diffraction (PXRD) measurements on samples synthesized via deposition from aqueous solution. Two possible monoclinic phases are considered, with closely related but symmetrically different crystal structures, based on those of the minerals malachite [Cu2CO3(OH)2] and rosasite [Cu1.5Zn0.5CO3(OH)2], as well as an orthorhombic phase that can be seen as a common parent structure for the two monoclinic phases, and a triclinic phase with the structure of the mineral kolwezite [Cu1.34Co0.66CO3(OH)2]. The DFT simulations predict that the rosasite-like and malachite-like phases are two different local minima of the potential energy landscape for Co2CO3(OH)2 and are practically degenerate in energy, while the orthorhombic and triclinic structures are unstable and experience barrierless transformations to the malachite phase upon relaxation. The best fit to the PXRD data is obtained using a rosasite model [monoclinic with space group P1121/ n and cell parameters a = 3.1408 (4) Å, b = 12.2914 (17) Å, c = 9.3311 (16) Å and γ = 82.299 (16)°]. However, some features of the PXRD pattern are still not well accounted for by this refinement and the residual parameters are relatively poor. The relationship between the rosasite and malachite phases of Co2CO3(OH)2 is discussed and it is shown that they can be seen as polytypes. Based on the similar calculated stabilities of these two polytypes, it is speculated that some level of stacking disorder could account for the poor fit of the PXRD data. The possibility that Co2CO3(OH)2 could crystallize, under different growth conditions, as either rosasite or malachite, or even as a stacking-disordered phase intermediate between the two, requires further investigation. [ABSTRACT FROM AUTHOR]

An unusually rich occurrence of supergene minerals, represented by azurite, baryte, cerussite, Zn-rich malachite, rosasite, smithsonite and wulfenite was recently identified at the subsurface parts of the Nová Anton epithermal ore vein near Hodruša-Hámre, Štiavnické vrchy Mts., Slovak Republic. Azurite is rare and it forms bright blue crystalline crusts, which consists of thin tabular crystals up to 2 mm. It is associated together with malachite, cerussite and smithsonite. Baryte occurs only infrequently as white, thin tabular crystals up to 5 mm growing on smithsonite. Cerussite is relatively abundant supergene mineral, especially in the proximity of relicts of primary galena. It forms clear to white, well-developed, acicular, prismatic or tabular crystals up to 1.2 cm or massive aggregates and rims up to 3 cm, which are often associated together with malachite and rosasite. Zn-rich malachite is very common supergene mineral at the studied locality and it occurs as pale green to greenish-blue hemispherical or radial aggregates up to 1 cm or crystalline crusts and coatings, which cover areas up to 100 cm². It is often associated with cerusite or smithsonite with rosasite, rarely also together with wulfenite or azurite. The unit-cell parameters of Zn-rich malachite refined from the powder X-ray diffraction data (for the monoclinic space group P21/a) are: a = 9.459(5) Å, b = 11.979(4) Å, c = 3.219(1) Å, β = 97.84(with)° 2 V = 361.3(3) Å3. It contain up to 0.18 apfu of Zn. Rosasite is relatively common species. It forms bluish-green to pale blue, hemispherical aggregates up to 7 mm with radial internal structure, which are often grouped to the botryoidal crusts covering areas up to 50 cm². Rosasite is often associated with smithsonite and Zn-rich malachite. Its refined unit-cell parameters (for the monoclinic space group P21/a) are: a = 12.890(8) Å, b = 9.342(7) Å, c = 3.164(2) Å, β = 110.26(2)° with V = 357.4(4) ų. Two types of rosasite can by distinguished by chemical composition. Predominant is Zn-rich phase with the Cu/Zn molar ratio in the range of 1.24 - 1.66 (1.11 - 1.25 apfu Cu, 0.75 - 0.89 apfu Zn). Cu-rich rosasite is infrequent and its Cu/Zn molar ratio vary from 3.32 to 3.61 (1.54 - 1.57 apfu Cu, 0.43 - 0.46 apfu Zn). Smithsonite is very common mineral, which is associated mainly with Zn-rich malachite and rosasite. It occurs as white, pale green to pale blue botryoidal crusts, which often consists of rounded rhombohedral or scalenohedral crystals up to 3 mm in size. Except of major Zn, elevated content of Cu (up to 0.08 apfu), and minor contents of Ca (up to 0.02 apfu) and K, Pb, Mg (all up to 0.01 apfu) were detected in smithsonite. Wulfenite is relatively abundant species and it forms orange to yellow, dipyramidal, often hemihedral or tabular crystals up to 1 cm. It was identified by PXRD and its refined unit-cell parameters (for the tetragonal space group I41/a) are: a = 5.438(5) Å, c = 12.1160(7) Å and V = 358.3(3) ų. Its chemical composition is close to the theoretical end member, PbMoO4. Well-developed supergene zones in-situ, especially with the abudance of supergene Cu and Zn carbonates are not typical for the epithermal ore veins in the Banská Štiavnica ore district. The origin of relatively well developed and rich supergene zone in-situ at the Nová Anton vein is directly linked with the fact, that upper parts of this vein are hosted in limestone. [ABSTRACT FROM AUTHOR]

Cu/Zn/Al mixed oxides catalysts were obtained from their corresponding layered precursors synthesized by coprecipitation of components varying M(II)/M(III) molar ratios of 2, 3, and 4 while maintaining Cu2+/Zn2+ molar ratio at 1.0. Crystalline phases concentration in the precursors was determined by Rietveld refinement analysis. Hydrotalcite (HTLc) phase concentration decreased from 79 to 32 wt % as M(II)/M(III) molar ratio increased from 2 to 4, respectively. A constant value of M(II)/M(III) molar ratio of 1.3–1.4 was determined for HTLc formation independently of the M(II)/M(III) molar ratio used for the synthesis. The excess of M(II), Cu and Zn components, segregate as Rosasite phase. Therefore, mixed oxides with different surface properties were obtained depending on the precursor crystalline phase component. Precursor with mainly HTLc phase generates mostly a homogenous Cu/Zn/Al mixed oxide where Al atoms hinder Cu reduction. On that sample no Cu0 was detected by XPS, then, hydrogen consumption during its reduction process was related to the presence of anionic vacancies, where H 2 can be heterolytically dissociated and stored in its hydric form, generating highly active hydro/dehydrogenation sites, with highest Lewis acidity. When the mixed oxides come from a precursor with mainly Rosasite phase, mixed oxides decompose into Cu0, ZnO, and Al 2 O 3 during reduction, where metallic Cu0 acts as dehydrogenating sites during ethanol dehydrogenation to acetaldehyde. In fact, higher Cu surface concentration favors the dehydrogenation route, increasing the yield towards acetaldehyde, whereas a high Al surface concentration enhances the dehydration path increasing diethyl ether yield. [Display omitted] • Cu/Zn/Al mixed oxides were obtained from layered precursors of HTLc and rosasite. • Surface properties of mixed oxide depend on the precursor composition. • Anionic vacancy sites are generated during reduction process. • Vacancies sites can dissociate H 2 and stored it. • Ethanol dehydrogenation to acetaldehyde occurs over vacancy sites. [ABSTRACT FROM AUTHOR]

An interesting (sub)recent supergene Cu-Zn mineral association was found at the abandoned gallery „Země zaslíbená" at the Mědník hill, Měděnec, Krušné hory Mountains, Czech Republic. Minerals of the serpierite - devillite solid solution form light to pale blue spherical aggregates up to 2 mm in size composed by thin tabular to acicular crystals. Serpierite is monoclinic, space group C2/cwith a 22.32(2), b 6.172(3), c 22.11(2) Å,β 114.02(6)° and V 2782(6) ų; devillite is monoclinic, space group P2/c with a 20.858(5), b 6.168(3), c 22.09(1) Å β 102.71(3)° and V 2773(2) ų. Brochantite forms green irregular crystalline coatings up to 2 mm in size and prismatic crystals up to 0.2 mm; it represents MDO polytype with monoclinic space group P2/a and a 13.128(1), b 9.8627(8), c 6.0345(7) Å,β 103.306(8)°, V 760.3(1) ų. Rare woodwardite forms thin light greenish blue coatings at the area up to 2 x 5 mm; only two very broad diffraction maxima (8.483/100 and 4.224/31 A) were found in its X-ray powder pattern. Aurichalcite occurs as rare tiny light blue hemispherical aggregates with diameter up to 0.5 mm; it is monoclinic, space group P2/m with a 13.832(7), b 6.421(3), c 5.289(3) Å,β 100.97(4)° and V461.1(4) ų. Rosasite forms rare light green hemispherical aggregates with diameter up to 0.2 mm; it is monoclinic, space group P2/a with a 12.850(5), b 9.348(1), c 3.144(3) Å,β 110.31(5)° and V 354.2(5) A³. Smithsonite occurs as white very thin coatings and tiny hemispherical aggregates, it is trigonal, space group R-3c with a 4.6687(3), c 15.098(1) Å and V 285.00(4) ų. X-ray powder diffraction patterns and quantitative chemical composition for determined mineral phases are given in the paper. [ABSTRACT FROM AUTHOR]

Rare supergene Cu-Zn carbonates, aurichalcite and rosasite, were found in 2007 in remnants of mine dumps of abandoned ore deposit at slope of the Sachrův hřbet hill above Horní Rokytnice (part of Rokytnice ned Jizerou), western Krkonoše Mountains, northern Bohemia, Czech Republic. Aurichalcite forms traslucent crystalline aggregates up to 1 cm in size with markedly sky-blue surface. Its elongated and thinly tabular crystals up to 1.5 mm in length are very brittle with a perfect cleavage and distinct pearly luster. They are transparent and colourless with light bluish tint. Aurichalcite is monoclinic, space group P21lm, the unit-cell parameters refined from X-ray powder data are: a = 13.812(1), b = 6.4041(8), c = 5.8060(8) Å, β = 100.71(1),° V = 461.14(9) ų. Chemical analyses yielded the average composition CaO 0.01, FeO 0.05, PbO 0.74, CuO 15.90, MnO 0.02, ZnO 51.61, Sb2O3 0.04, CO2 (14.69), SiO2 0.06, As2O5 0.06, SO3 0.11, H2O (9.02), total (92.32) wt. %, corresponding to the formula (Zn3.78Cu1.19Pb0.02)∑4.99[CO3)1.99 (SO4)0.01]∑2.00(OH)5.97 on the basis of 5 atoms in cation sites. Rosasite forms thin, irregular coatings up to 1 mm² on aurichalcite and rarely hemispherical aggregates up to 0.3 mm in size. It is translucent to opaque with indistinct greyish green colour and pearly luster. Surface of its aggregates ere ussualy smooth, its columnar crystals up to 10 µm were observed only rarely. The average results of five chemical analyses are: CaO 0.02, FeO 0.03, PbO 0.38, CuO 39.01, MnO 0.01, ZnO 22.77, CO2 (16.90), SiO2 0.06, As2O5 0.03, P2O5 0.11, SO3 0.04, H2O (6.90), total (86.26) wt. % corresponding to (Cu1.27Zn0.72)∑1.99(CO3)0.99(OH)1.99 on the basis of 2 atoms in cation sites. Chemical composition of both studied Cu-Zn carbonates is compared with published data. The succession of origin of supergene minerals inferred from the samples studied is as follows: hemimorphite → aurichalcite → rosasite. [ABSTRACT FROM AUTHOR]

Abstract: Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440cm−1 is assigned to the CO3 2− antisymmetric stretching vibration. An additional band is resolved at 1335cm−1. An intense sharp Raman band at 1092cm−1 is assigned to the CO3 2− symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442cm−1 shifting to lower wavenumbers with thermal treatment. A band observed at 870cm−1 with a band of lesser intensity at 842cm−1 shifts to higher wavenumbers upon thermal treatment and is observed at 865cm−1 at 400°C and is assigned to the CO3 2− mode. No bending modes are observed in the Raman spectra for smithsonite. The band at 746cm−1 shifts to 743cm−1 at 400°C and is attributed to the CO3 2− in phase bending modes. Two infrared bands at 744 and around 729cm−1 are assigned to the in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO6 octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991cm−1 in both the IE and infrared spectra are attributed to combination bands. [Copyright &y& Elsevier]

Abstract: Hydrozincite and smithsonite were synthesised by controlling the partial pressure of CO2. Previous crystallographic studies concluded that the structure of hydrozincite was a simple one. However both Raman and infrared spectroscopy show that this conclusion is questionable. Multiple bands are observed in both the Raman and infrared spectra in the (CO3)2− antisymmetric stretching and bending regions of hydrozincite showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the hydrozincite structure. Multiple OH stretching vibrations centred in both the Raman and infrared spectra show that the OH units in the hydrozincite structure are non-equivalent. The Raman spectrum of synthetic smithsonite is a simple spectrum characteristic of carbonate with Raman bands observed at 1408, 1092 and 730cm−1. The symmetry of the carbonate anion in hydrozincite is C 2v or C s . This symmetry reduction results in multiple bands in both the symmetric stretching and bending regions. The intense band of hydrozincite at 1062cm−1 is assigned to the ν 1 (CO3)2− symmetric stretching mode. Three Raman bands assigned to the ν 3 (CO3)2− antisymmetric stretching modes are observed for hydrozincite at 1545, 1532 and 1380cm−1. Multiple infrared or Raman bands are observed in 800–850cm−1 and 720–750cm−1 regions and are attributed to ν 2 and ν 4 bending modes confirming the reduction of the carbonate anion symmetry in the hydrozincite structure. A Raman band for hydrozincite at 980cm−1 is attributed to the δ OH deformation mode. [Copyright &y& Elsevier]

Abstract: The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals from spectral characteristics is demonstrated. NIR spectroscopy can be regarded as an alternative tool for structure analysis. The spectra show that rosasite group minerals with different cations can be distinguished. Ni2+ in nullaginite [Ni2(CO3)(OH)2] is conspicuous through a single broad band absorption feature at 8525cm−1, extended from 11,000 to 7000cm−1. The effect of Ni on Cu is seen in the spectrum of glaukosphaerite [(Cu, Ni)2(CO3)(OH)2] both by a red shift of the spectrum and reduction in intensity of bands with variable positions of band maxima for Cu2+ at 6995cm−1and Ni2+ at 7865cm−1. The spectrum of rosasite [(Cu, Zn)2(CO)3(OH)2] is characterised by Cu2+ band at 7535cm−1. Kolwezite [(Cu, Co)2(CO)3(OH)2] is a spectral mixture of Cu and Co but optically separated by Co2+ and Cu2+ peaks at 8385 and 7520cm−1. Vibrational spectra of carbonates show a number of bands in the 7000–4000cm−1 region attributable to overtones, combination of OH stretching and deformation modes. They appear to be uniform in nature since the structure of rosasite group minerals is identical. The complexity of these features varies between samples because of the variation in composition and hence is useful for discriminating different hydrous carbonates. [Copyright &y& Elsevier]

Abstract: Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by a combination of infrared and Raman spectroscopy. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at ∼3401 and 3311cm−1. Two intense bands observed at ∼1096 and 1046cm−1 are assigned to ν 1(CO3)2− symmetric stretching vibration and the δ OH deformation mode. Multiple bands are found in the 800–900 and 650–750cm−1 regions attributed to the ν 2 and ν 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s. A band at ∼560cm−1 is assigned to a CuO stretching mode. [Copyright &y& Elsevier]

Abstract: Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by powder X-ray diffraction, scanning electron microscopy and infrared spectroscopy. X-ray diffraction shows the minerals to be complex mixtures with more than one rosasite mineral observed in each sample. SEM analysis shows the minerals to be fibrous in nature and the use of EDAX enabled the chemical composition of the minerals to be determined. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at ∼3401 and 3311cm−1. Two intense bands observed at ∼1096 and 1046cm−1 are assigned to ν 1 (CO3)2− symmetric stretching vibration and the δ OH deformation mode. Multiple bands are found in the 800–900 and 650–750cm−1 regions attributed to the ν 2 and ν 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s . A band at ∼560cm−1 is assigned to a CuO stretching mode. [Copyright &y& Elsevier]