ALBERT

Description: The Journal of Physical Chemistry B DOI: 10.1021/jp308280d

Description: Nordgauite, MnAl2(PO4)2(F,OH)2{middle dot}5H2O, is a new secondary phosphate from the Hagendorf-Sud pegmatite, Bavaria, Germany. It occurs as white to off-white compact waxy nodules and soft fibrous aggregates a few millimetres across in altered zwieselite-triplite. Individual crystals are tabular prismatic, up to 200 {micro}m long and 10 {micro}m wide. Associated minerals include fluorapatite, sphalerite, uraninite, a columbite-tantalite phase, metastrengite, several unnamed members of the whiteite-jahnsite family, and a new analogue of kingsmountite. The fine-grained nature of nordgauite meant that only limited physical and optical properties could be obtained; streak is white; fracture, cleavage and twinning cannot be discerned. Dmeas. and Dcalc. are 2.35 and 2.46 g cm-3, respectively; the average RI is n = 1.57; the Gladstone-Dale compatibility is -0.050 (good). Electron microprobe analysis gives (wt.%): CaO 0.96, MgO 0.12, MnO 14.29, FeO 0.60, ZnO 0.24, Al2O3 22.84, P2O5 31.62, F 5.13 and H2O 22.86 (by CHN), less F=O 2.16, total 96.50. The corresponding empirical formula is (Mn0.90Ca0.08Fe0.04Zn0.01Mg0.01)-{Sigma}1.04Al2.01(PO4)2[F1.21,(OH)0.90]{Sigma}2.11{middle dot}5.25H2O. Nordgauite is triclinic, space group P[IMG]f1.gif" ALT="Formula" BORDER="0"〉, with the unit-cell parameters: a = 9.920(4), b = 9.933(3), c = 6.087(2) A, = 92.19(3), {beta} = 100.04(3), {gamma} = 97.61(3){degrees}, V = 584.2(9) A3 and Z = 2. The strongest lines in the XRD powder pattern are [d in A (I) (hkl)] 9.806 (100)(010), 7.432 (40)(1[IMG]f1.gif" ALT="Formula" BORDER="0"〉0), 4.119 (20)(210), 2.951 (16)(0[IMG]f2.gif" ALT="Formula" BORDER="0"〉1), 4.596 (12)(2[IMG]f1.gif" ALT="Formula" BORDER="0"〉0), 3.225 (12)(220) and 3.215 (12)(121). The structure of nordgauite was solved using synchrotron XRD data collected on a 60 {micro}m x3 {micro}m x4 {micro}m needle and refined to R1 = 0.0427 for 2374 observed reflections with F 〉 4{sigma}(F). Although nordgauite shows stoichiometric similarities to mangangordonite and kastningite, its structure is more closely related to those of vauxite and montgomeryite in containing zig-zag strings of corner-connected Al-centred octahedra along [011], where the shared corners are alternately in cis and trans configuration. These chains link through corner-sharing with PO4 tetrahedra along [001] to form (100) slabs that are interconnected via edge-shared dimers of MnO6 polyhedra and other PO4 tetrahedra.

Description: The name ‘tobermorites’ includes a number of calcium silicate hydrate (C-S-H) phases differing in their hydration state and sub-cell symmetry. Based on their basal spacing, closely related to the degree of hydration, 14, 11 and 9 Å compounds have been described. In this paper a new nomenclature scheme for these mineral species is reported. The tobermorite supergroup is defined. It is formed by the tobermorite group and the unclassified minerals plombièrite, clinotobermorite and riversideite. Plombièrite (‘14 Å tobermorite’) is redefined as a crystalline mineral having chemical composition Ca 5 Si 6 O 16 (OH) 2 ·7H 2 O. Its type locality is Crestmore, Riverside County, California, USA. The tobermorite group consists of species having a basal spacing of ~11 Å and an orthorhombic sub-cell symmetry. Its general formula is Ca 4+ x (Al y Si 6– y )O 15+2 x – y ·5H 2 O. Its endmember compositions correspond to tobermorite Ca 5 Si 6 O 17 ·5H 2 O ( x = 1 and y = 0) and the new species kenotobermorite, Ca 4 Si 6 O 15 (OH) 2 ·5H 2 O ( x = 0 and y = 0). The type locality of kenotobermorite is the N'Chwaning II mine, Kalahari Manganese Field, South Africa. Within the tobermorite group, tobermorite and kenotobermorite form a complete solid solution. Al-rich samples do not warrant a new name, because Al can only achieve a maximum content of 1/6 of the tetrahedral sites ( y = 1). Clinotobermorite, Ca 5 Si 6 O 17 ·5H 2 O, is a dimorph of tobermorite having a monoclinic sub-cell symmetry. Finally, the compound with a ~9 Å basal spacing is known as riversideite. Its natural occurrence is not demonstrated unequivocally and its status should be considered as "questionable". The chemical composition of its synthetic counterpart, obtained through partial dehydration of tobermorite, is Ca 5 Si 6 O 16 (OH) 2 . All these mineral species present an order-disorder character and several polytypes are known. This report has been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification.

Description: Author(s): J. Alvarez-Muñiz, A. Berlin, M. Bogdan, M. Boháčová, C. Bonifazi, W. R. Carvalho, Jr., J. R. T. de Mello Neto, P. Facal San Luis, J. F. Genat, N. Hollon, E. Mills, M. Monasor, P. Privitera, L. C. Reyes, B. Rouille d’Orfeuil, E. M. Santos, S. Wayne, C. Williams, E. Zas, and J. Zhou We present a search for microwave emission from air showers induced by ultrahigh energy cosmic rays with the microwave detection of air showers experiment. No events were found, ruling out a wide range of power flux and coherence of the putative emission, including those suggested by recent laborato... [Phys. Rev. D 86, 051104] Published Wed Sep 26, 2012

Description: An unexpected role for mixotrophs in the response of peatland carbon cycling to climate warming Scientific Reports, Published online: 25 November 2015; doi:10.1038/srep16931