Sequences of charged sheets in rectorite

Other| April 01, 1995 Sequences of charged sheets in rectorite Hans J. Jakobsen; Hans J. Jakobsen University of Aarhus, Department of Chemistry, Aarhus, Denmark Search for other works by this author on: GSW Google Scholar Niels C. Nielsen; Niels C. Nielsen Search for other works by this author on: GSW Google Scholar Holger Lindgreen Holger Lindgreen Search for other works by this author on: GSW Google Scholar American Mineralogist (1995) 80 (3-4): 247–252. https://doi.org/10.2138/am-1995-3-406 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Hans J. Jakobsen, Niels C. Nielsen, Holger Lindgreen; Sequences of charged sheets in rectorite. American Mineralogist 1995;; 80 (3-4): 247–252. doi: https://doi.org/10.2138/am-1995-3-406 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Two rectorite samples, a Na- and Ca-rich rectorite (sample 1) from Beatrix Mine, South Africa, and a Na-rich rectorite (sample 2) from Garland County, Arkansas, have been investigated quantitatively by solid-state 23Na,27Al, and 29Si magic-angle spinning (MAS) NMR spectroscopy, total chemical dissolution, cation exchange, and X-ray diffraction (XRD). Comparison of modeled and experimental diffractograms shows that both rectorite samples have a mica to smectite ratio of 1:1 and an ideal ordering in units of one mica plus one smectite layer. The average thicknesses of the coherent scattering domains are ten and eight 2:1 layers for samples 1 and 2, respectively. Quantification of the 23Na,27 Al, and 29Si MAS NMR spectra has allowed determination of the compositions for the octahedral sheets and for the mica (paragonite and margarite) and smectite tetrahedral sheets and determination of the distribution of interlayer Na+ ions between paragonite and margarite interlayers. Each 2:1 layer has an octahedral sheet of weak positive charge sandwiched between two tetrahedral sheets of weak and strong negative charge. The top and bottom tetrahedral sheets of the coherent scattering domains have strong negative charges and very high cation-exchange capacities for sample 1 and low negative charges for sample 2. Sample 1 is a three-component mixed layer (margarite, paragonite, and smectite), and sample 2 a two-component mixed layer (paragonite and smectite). This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.