Laffittite, AgHgAsS 3 , is monoclinic, space group Aa, a = 7.732(3), b = 11.285(7), c = 6.643(4)Aa, beta = 115.16(3) degrees , Z = 4. The strongest lines in the X-ray powder pattern are 3.512(100)(200), 3.202(78)(031,1 (super -) 31), 3.015(69)(002), 2.685(67)(2 (super -) 31), 1.898(29)(1 (super -) 33,2 (super -) 33, 2.136(18)(231,3 (super -) 31), 3.633(16)(111), 1.889(14)(4 (super -) 11). Hydrothermally synthesized at 350 degrees C under 10,000 psi pressure for 140 hours. The crystal structure of laffittite is a superstructure based upon the PbS structure. Metal-sulfur bonds form a hexagonal ring of one formula unit; the rings link to each other by sharing all edges forming a sheet parallel to (100); the sheets link up and down by Hg-S and Ag-S bonds to form a three-dimensional network. The structure is closely related to that of marrite, PbAgAsS 3 .--Modified journal abstract.

Abstract Gerstleyite is monoclinic, a=9.911(8), b=23.05(2), c=7.097(8) Å, β=127.85(7) °, space group Cm, and Z=2. All Sb atoms have essentially 3-fold coordination, forming trigonal SbS3 pyramids. The SbS3 pyramids share corners to form a complex chain parallel to [100]. Na–S bonds cross-link the chains into a slab structure parallel to (010). Water molecules coordinate only to Na atoms.

Other| January 01, 1977 The crystallography of Patellina corrugata Williamson; a-axis preferred orientation Kenneth M. Towe; Kenneth M. Towe Smithsonian Institution National Museum of Natural History, Department of Paleobiology, Washington, DC, United States Search for other works by this author on: GSW Google Scholar Wulf-Ulrich Berthold; Wulf-Ulrich Berthold Search for other works by this author on: GSW Google Scholar Daniel E. Appleman Daniel E. Appleman Search for other works by this author on: GSW Google Scholar Journal of Foraminiferal Research (1977) 7 (1): 58–61. https://doi.org/10.2113/gsjfr.7.1.58 Article history first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Kenneth M. Towe, Wulf-Ulrich Berthold, Daniel E. Appleman; The crystallography of Patellina corrugata Williamson; a-axis preferred orientation. Journal of Foraminiferal Research 1977;; 7 (1): 58–61. doi: https://doi.org/10.2113/gsjfr.7.1.58 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.

________________________ Introduction and acknowledgments ____________ Merumite _________________________ Nature and occurrence -____-________ Previous studies _________________ Chemistry _______________________ Older analyses _____________________ Recent analyses _________________ Isotopic study _________________ X-ray powder data ____________________________ Petrography ________________________ Eskolaite ___________________________________ Occurrence in Finland and Guyana, and (possibly) Siberia ________________________ Chemistry __________________________ Guyanaite __________________________________ Occurrence in Guyana and Finland, and synthesis Chemistry _____________ Analyses ________________________________ Thermal behavior _____________________________ X-ray powder data ____________________ Bracewellite, CrOOH ______________________________ Occurrence and identification ______________ Chemistry _______________________ Analysis ___________________ Page Page 1 Bracewellite, CrOOH Continued 1 Electron-probe study __ __ __ 16 1 X-ray powder data ___________ __ -16 1 Grimaldiite CrOOH and mcconnellite CrOOCu 17 6 Occurrence _______________ ___ 17 7 Physical properties _____ _ __ 18 7 Chemistry _____________ 18 7 Electron-probe analysis _____ -_ _____ _ 19 7 X-ray data __________________ 19 7 Previous syntheses of rhombohedral CrOOH and 8 CrOOCu _________________________ 19 9 Relation of mcconnellite to delafossite 20 y-CrOOH (synthetic) ____________ 21 9 Synthesis _______________ 21 10 X-ray powder data and cell constants _ 22 10 Chromian gahnite ___________________ _ _ 22 10 Properties _____________________-__ 22 11 Electron-probe analysis _______ __ _ 23 11 X-ray data _________________________ 23 12 Other chromian gahnites and zincian chromites _ __ 23 13 Chromian pyrophyllite __________ _ __ _ 24 13 Gold (and silver) in merumite ________ _ _ 24 13 Accessory minerals from Director Creek _ _ 24 15 Crystallographic relationships of CrOOH compounds 28 15 References cited _________________ __ 28

Bond distances and angles in isostructural, ordered clinopyroxenes are compared for eight compositions, based on five new and three published crystal-structure refinements from X-ray diffraction data. Unit-cell parameters and configuration of the silicate chains are directly correlated with cation composition and distribution in the M2 and M1 sites.

Triclinic ulexite crystals contain isolated borate polyanions [B 5 O 6 (OH) 6 ] 3- related to the well known pentaborate polyanion [B 5 O 6 (OH) 4 ] - by addition of two hydroxyl groups to two opposite B-O triangles. The isolated ulexite polyanions form the [B 5 O 7 (OH) 4 ] n 3 n - chains previously found in crystals of the related mineral probertite, NaCaB 5 O 7 (OH) 4 ⋅3H 2 O.

The crystal structure of meta-torbernite, Cu(UOrPODz.8HgO, has been determined and refined by three-dimensional least-squares analysis. The structure consists of infinite (UOrPOt""sheets isostructural rn'ith those of meta-autunite(I) and abernathyite. Between the sheets lie squares of four water molecules. Two of the four squares per unit ceII coordinate the two copper atoms. The other two squares do not coordinate a cation but are hydrogen bonded together in the same manner as those in the abernathyite structure. Each water molecule of the Cu(H:O)a squares is hydrogen bonded to a water molecule of an adjacent (HzO)a square and to a phosphate oxygen atom. Each water molecule of the (H:O)a seuares is hydrogen bonded to two other water molecules within the square, to an adjacent Cu(H:O)r water molecule, and to a phosphate oxygen atom. The copper atoms are also bonded to two uranyl-oxygen atoms; thus the coordination polyhedra about the copper cations is in the form of an asymmetrical tetragonal dipyramid. X-ray powder data for meta-torbemite are given. Unit-cell data for meta-zeunerite, Cu(UOzAsOr)z.SHzO, are also presented.

Triclinic ulexite crystals contain isolated borate polyanions [B5O6(OH)6]3- related to the well known pentaborate polyanion [B5O6(OH)4]- by addition of two hydroxyl groups to two opposite B-O triangles. The isolated ulexite polyanions form the [B5O7(OH)4]n3n- chains previously found in crystals of the related mineral probertite, NaCaB5O7(OH)4·3H2O.

The crystal structures of the five known members of the series Ca2B6O11·xH2O (x = 1, 5, 5, 7, 9, and 13) have been refined by full-matrix least-squares techniques, yielding bond distances and angles with standard errors of less than 0·01 Å and 0·5°, respectively. The results illustrate the crystal chemical principles that govern the structures of hydrated borate compounds. The importance of hydrogen bonding in the ferroelectric transition of colemanite is confirmed by more accurate proton assignments.