Ktenasite, another mineral with∞2[(Cu,Zn)2(OH)3O]−octahedral sheets (original) (raw)
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American Mineralogist, 2012
This paper reports on the occurrence and the crystal structure of kircherite, a new member of the cancrinite-sodalite group of minerals from Valle Biachella, Sacrofano community (Rome, Latium, Italy). The mineral occurs in association with sodalite, biotite, iron oxides, titanite, fluorite, and a pyrochlore-group mineral. The groundmass of the ejectum consists essentially of K-feldspar with subordinate plagioclase. Kircherite (3 mm as largest size) is observed within miarolitic cavities of the rock and typically occurs as parallel associations of hexagonal, thin, tabular colorless to light-gray transparent crystals; it is non-pleochroic and uniaxial negative, with ω = 1.510(2) and ε = 1.502(2). D calc is 2.457 g/cm 3 . Kircherite is trigonal with a = 12.8770 , c = 95.244(6) Å, V = 13677(1) Å 3 , Z = 1. The structure has been refined in the trigonal space group R32, obtaining a R-value of 8.5% on 8131 reflections with I/σI > 2. The strongest seven reflections in the X-ray powder pattern are [d in Å (I %) (hkl)]: 3.717 (3 0 0), 2.648 (100) (2 1 28; 0 0 36), 3.232 (65) (2 1 19), 3.584 (60) (1 2 14), 3.604 (53) (1 0 25), 3.799 (52) (1 2 11), 3.220 (38) (2 2 0). The single-crystal FTIR spectrum rules out OH groups and shows the presence of H 2 O and CO 2 molecules in the structural cages of the mineral. Chemical analysis gives (in wt%): SiO 2 32.05, Al 2 O 3 27.13, FeO 0.07, K 2 O 4.38, CaO 8.75, Na 2 O 13.62, MgO 0.01, MnO 0.02, TiO 2 0.01, SO 3 12.87, Cl 0.35, F 0.05, total 99.82. The empirical formula calculated on the basis of Σ(Si+Al) = 216 apfu is (Na 89.09 O, which corresponds to the ideal formula [Na 90 Ca 36 K 18 ] Σ=144 (Si 108 Al 108 O 432 )(SO 4 ) 36 ⋅6H 2 O.
The Canadian Mineralogist, 2006
The crystal structure of Ag-bearing paděraite, ideally Cu 7 (Ag 0.33 Pb 1.33 Bi 11.33 ) ⌺13 S 22 , a 17.585(4), b 3.9386(9), c 28.453(7) Å,  105.41(1)°, V 1899.8(8) Å 3 , space group P2 1 /m and Z = 2, from a skarn deposit at Băiţa Bihor in Romania, has been solved by direct methods and refi ned to an R 1 index of 7.72% for 2429 unique refl ections [F o ≥ 4(F o )] measured with MoK␣ X-radiation on a three-circle diffractometer equipped with a CCD detector. The crystal structure of Ag-free, Cu-enriched paděraite, ideally Cu 7 (Cu 0.33 Pb 1.33 Bi 11.33 ) ⌺13 S 22 , a 17.573(2), b 3.9426(4), c 28.423(3) Å,  105.525(2)°, V 1897.3(6) Å 3 , space group P2 1 /m and Z = 2, from a rare-metal granitic pegmatite at Swartberg, South Africa, has been solved by direct methods and refi ned to an R 1 index of 5.04% for 3200 unique refl ections [F o ≥ 4(F o )]. In the crystal structures, there are 12 Bi sites, one Pb site, seven triangular and fl at-tetrahedral Cu sites and 22 S positions. The crystal structure, in most features corresponding to that described earlier, can be represented as a intergrowth of kupčíkite-like "K slabs" and "Q slabs", which on their own make up a structure related to nordströmite or kobellite. We provide the chemical formulae and unit cells of potential KQ n homologues of paděraite, as well as of regular intergrowths of paděraite and cuprobismutite homologous series.
Posnjakite: 2 ∞[Cu4(OH)6(H2O)O] octahedral sheets in its structure
Zeitschrift für Kristallographie - Crystalline Materials, 1979
The crystal structure of posnjakite (space group Pa, a = 10.578, b = 6.345, c = 7.863 Å, β = 117.98°) was determined by direct methods and refined to a final R value of 0.05. The structure is characterized by corrugated sheets of distorted copper octahedra with crystal chemical formula 2 ∞Cu4(OH)6(H2O)O]. Sulphate groups are connected to one side of the octahedral sheet by corner sharing. The resultant composite octahedraltetrahedral layers are connected to each other by hydrogen bonds. The crystal chemical formula of posnjakite is Cu4(SO4)(OH)6 · H2O with two such units in the unit cell. The relations of posnjakite with other copper sulphate hydrates are noted and discussed.
Crystal chemistry and polytypism of tyrolite
American Mineralogist, 2006
The crystal structures of the 1M and 2M polytypes of tyrolite have been solved from single-crystal X-ray diffraction data. The structure of tyrolite-1M [monoclinic, P2/c, a = 27.562(3), b = 5.5682 , c = 10.4662(15) Å, β = 98.074(11)°, V = 1590.3(3) Å 3 ] has been reÞ ned to R 1 = 0.086 on the basis of 2522 unique observed reß ections collected using synchrotron radiation at the Swiss-Norwegian beamline BM01 of the European Synchrotron Research Facility (SNBL at the ESRF). The structure of tyrolite-2M [monoclinic, C2/c, a = 54.520(6), b = 5.5638(6), c = 10.4647(10) Å, β = 96.432(9)°, V = 3154.4(6) Å 3 ] has been reÞ ned to R 1 = 0.144 on the basis of 2666 unique observed reß ections obtained from a non-merohedrally twinned crystal using in-house X-ray radiation and a STOE IPDS II imageplate diffractometer. The structures are based upon complex nanolayers consisting of Cu, As, and Ca coordination polyhedra. The core of the nanolayer is a copper arsenate substructure consisting of A and B sublayers. The B sublayer consists of chains of edge-sharing Cu octahedra running along the b axis. The A sublayer contains trimeric units of Cu octahedra sharing corners with AsO 4 tetrahedra. Two adjacent A sublayers are linked by the octahedral chains of the B sublayer resulting in formation of the 18 Å thick ABA slab. The ABA slab is sandwiched between sublayers of Ca 2+ cations and H 2 O molecules. Adjacent nanolayers are connected by hydrogen bonds to the interlayer species (carbonate anions and H 2 O molecules). The structures of tyrolite-1M and tyrolite-2M differ by the stacking sequence of the nanolayers only. The adjacent nanolayers in tyrolite-2M are shifted by b/2 = 2.8 Å in comparison to the relative position of the nanolayers in tyrolite-1M. The structural formula of tyrolite can be written as [Ca 2 Cu 9 (AsO 4 ) 4 (OH) 8 (CO 3 )(H 2 O) 11 ](H 2 O) x where x = 0-1.
THE CRYSTAL STRUCTURE OF FRANZINITE, THE TEN-LAYER MINERAL OF THE CANCRINITE GROUP
Canadian Mineralogist, 2000
Franzinite, ideally [(Na,K) 30 Ca 10 ][Si 30 Al 30 O 120 ](SO 4 ) 10 •2H 2 O, a feldspathoid belonging to the cancrinite group, has a tenlayer stacking sequence. Its structure was solved in the space group P321 to an R value of 5.96%. Cell parameters are a 12.916(1), c 26.543(3) Å. The framework, characterized by the stacking sequence ABCABACABC, contains regular alternations of two "cancrinite" and two "sodalite" cages along [0 0 z], and of two "sodalite" and one "losod" cages along [⅔ ⅓ z] and [⅓ ⅔ z]. The Si:Al ratio is equal to 1, and the framework has a perfectly ordered Si,Al distribution, as was found in liottite and afghanite, the 6-and 8-layer cancrinite-like minerals, respectively. The cages host a complex distribution of extra-framework cations (Ca, Na, K), (SO 4 ) 2anions, and H 2 O molecules. The "losod" cage contains two sulfate groups aligned along z and separated by a triplet of cations. Two additional triplets of cations are located around the two sulfate groups. The two bases of the cage are occupied by calcium atoms, which make favorable bond-distances with the apical atoms of oxygen of the SO 4 tetrahedra within the cage. The two "cancrinite" cages share a common base and contain a segment of the ...Na-H 2 O…Na-H 2 O.... chain, which is a characteristic feature of the cancrinite, vishnevite, and pitiglianoite structures. The "sodalite" cages host one sulfate group that is always disordered and displaced from the three-fold axis. The (Ca, K, Na) cations are distributed among various split sites, each one with partial occupancy, showing marked similarity with the "sodalite" cages of the (SO 4 ) 2--and S 2--bearing minerals with sodalitetype structure.
American Mineralogist, 2010
New discoveries of kuksite, Pb 3 Zn 3 Te 6+ P 2 O 14 , from the Black Pine mine, Montana, and Blue Bell claims, California, have enabled a detailed crystal-chemical study of the mineral to be undertaken. Single-crystal X-ray structure refinements of the structure indicate that it is isostructural with dugganite, Pb 3 Zn 3 Te 6+ As 2 O 14 , and joëlbruggerite, Pb 3 Zn 3 (Sb 5+ ,Te 6+ )As 2 O 13 (OH,O). Kuksite from the Black Pine mine crystallizes in space group P321, with unit-cell dimensions a = 8.392(1), c = 5.204(1) Å, V = 317.39(8) Å 3 , and Z = 1 (R 1 = 2.91% for 588 reflections [F o > 4σF] and 3.27% for all 624 reflections), while Blue Bell kuksite has the unit cell a = 8.3942 , c = 5.1847(4) Å, and V = 316.38(4) Å 3 (R 1 = 3.33% for 443 reflections [F o > 4σF] and 3.73% for all 483 reflections). Chemical analyses indicate that solid-solution series exist between kuksite, dugganite, and joëlbruggerite. Raman spectroscopic and powder X-ray diffraction data are also presented for samples from both occurrences.
Incorporation of Co in the rosasite-malachite carbonate group of minerals: crystal structure studies of kolwezite and of synthetic cobaltoan malachites-Manuscript Draft-Abstract: The crystal structure of kolwezite, (Cu,Co)2(CO3)(OH)2, has been refined by Rietveld method from synchrotron X-ray powder data. Kolwezite, P21/a, a = 12.201(1), b = 9.354(1), c = 3.1494(3) Å, ß= 98.922(7)°, is isostructural with rosasite, and its crystal structure was refined up to Rp = 4.56%, wRp = 6.51%. Because of the Jahn-Teller effect, Me1 polyhedron hosting Cu2+only is strongly distorted towards a (4+2) coordination, while Me2 octahedron, with major Co, is neatly a more regular one. Me2+ polyhedra are connected through edge-sharing, forming "ribbons" running along [001] direction. These ribbons are interconnected by corner sharing to form "corrugated" layers, interlinked by the carbonate groups, giving rise to an infinite framework structure, with notation M−M=M−T. The Rietveld study of synchrotron X-ray powder data of synthetic cobaltoan malachites shows a decrease in unit-cell volume, with an anisotropic contraction of unit-cell parameters, directly related to the increasing Co content. The major progressive shortening of apical bonds in Me2 octahedra, with consequent regularization of the Jahn-Teller distorted Cu octahedra, drives a progressive compacting of the malachite structure, the main factor accounting for volume contraction in cobaltoan malachites.
The Canadian Mineralogist, 2003
Kupčíkite, Cu 3.4 Fe 0.6 Bi 5 S 10 , a new mineral species, is found in the scheelite deposit of Felbertal, Austria, in a quartz gangue, in association with chalcopyrite, pyrrhotite, molybdenite, sphalerite and native bismuth, intergrown with makovickyite, cupromakovickyite, hodrushite, cuprobismutite and derivatives of the bismuthinite-aikinite series. The mineral is grey with metallic luster, brittle, and without cleavage. Mean micro-indentation hardness is 192 kg/mm 2 (Mohs hardness 3.3), and the calculated density is 6.42 g/cm 3 . In reflected light, it is grayish white; the anisotropy is moderate in air and strong in oil, and it does not show internal reflections. Reflectance values (in %) in air are, for R 1 and R 2 , 33.55, 40.56 at 470 nm, 33.92, 41.14 at 546 nm, 34.16, 41.35 at 589 nm, and 34.2, 41.32 at 650 nm. The average results of seven electron-microprobe analyses are: Cu 13.02, Fe 2.23, Ag 0.11, Cd 0.3, Bi 64.21, Sb 0.12, S 20.10, total 100.08 wt.%, corresponding to Fe 0.64 Cu 3.29 Ag 0.015 Cd 0.045 Sb 0.015 Bi 4.94 S 10.07 (basis: 19 atoms per formula unit). The simplified formula, in accordance with the crystal-structure analysis, is Fe 0.6 Cu 3.4 Bi 5 S 10 . The crystal structure was solved, to R = 4.1%, from single-crystal data obtained on a four-circle diffractometer with an area detector. Kupčíkite has a monoclinic cell with a 17.512(2), b 3.9103(4), c 12.869(1) Å,  108.56(1)°, V 835.4(1) Å 3 , space group C2/m, with Z = 2. The strongest lines in the calculated powder-diffraction pattern [d in Å (I)(hkl)] are: 6.028(and 2.683(5)(113). Its structure corresponds to the structure of synthetic Cu 4 Bi 5 S 10 ; the (Cu,Fe) position in the mineral is distinctly split. Kupčíkite is closely structurally related to cuprobismutite and hodrushite. It is the N = 1 member of the cuprobismutite series, whereas cuprobismutite is the N = 2 member. Hodrushite is composed of a regular 1:1 intergrowth of kupčíkite-like and cuprobismutite-like layers. In typical intergrowths with makovickyite or hodrushite, kupčíkite shows sharp straight boundaries with both of these phases, but where in contact with derivatives of the bismuthinite-aikinite series, the latter replace kupčíkite. In a rare occurrence of kupčíkite with cuprobismutite in the same aggregate, the cuprobismutite is replaced by kupčíkite.
Glikinite, Zn3O(SO4)2, a new anhydrous zinc oxysulfate mineral structurally based on OZn4 tetrahedra
Mineralogical Magazine, 2020
A new mineral glikinite, ideally Zn3O(SO4)2, was found in high-temperature exhalative mineral assemblages in the Arsenatnaya fumarole, Second scoria cone of the Great Tolbachik Fissure Eruption (1975–1976), Tolbachik volcano, Kamchatka Peninsula, Russia. Glikinite is associated closely with langbeinite, lammerite-β, bradaczekite, euchlorine, anhydrite, chalcocyanite and tenorite. It is monoclinic, P21/m, a = 7.298(18), b = 6.588(11), c = 7.840(12) Å, β = 117.15(3)°, V = 335.4(11) Å3 and R1 = 0.046. The eight strongest lines of the powder X-ray diffraction pattern [d in Å (I) (hkl)] are: 6.969(56)(00$\bar{1}$), 3.942(52)(101), 3.483(100)(00$\bar{2}$), 3.294(49)(020), 2.936(43)(120), 2.534(63)(201), 2.501(63)(20$\bar{3}$) and 2.395(86)(02$\bar{2}$). The chemical composition determined by electron-microprobe analysis is (wt.%): ZnO 42.47, CuO 19.50, SO3 39.96, total 101.93. The empirical formula calculated on the basis of O = 9 apfu is Zn2.07Cu0.97S1.98O9 and the simplified formula is ...