A Rietveld and infrared study of synthetic amphiboles along the potassium-richterite-tremolite join

Abstract

Other| August 01, 1997 A Rietveld and infrared study of synthetic amphiboles along the potassium-richterite-tremolite join Frank C. Hawthorne; Frank C. Hawthorne University of Manitoba, Department of Geological Sciences, Winnipeg, MB, Canada Search for other works by this author on: GSW Google Scholar Giancarlo Della Ventura; Giancarlo Della Ventura Terza Universita di Roma, Rome, Italy Search for other works by this author on: GSW Google Scholar Jean-Louis Robert; Jean-Louis Robert CNRS, Orleans, France Search for other works by this author on: GSW Google Scholar Mark D. Welch; Mark D. Welch Natural History Museum, London, United Kingdom Search for other works by this author on: GSW Google Scholar Mati Raudsepp; Mati Raudsepp University of British Columbia, Vancouver, BC, Canada Search for other works by this author on: GSW Google Scholar David M. Jenkins David M. Jenkins State University of New York at Binghamton, United States Search for other works by this author on: GSW Google Scholar American Mineralogist (1997) 82 (7-8): 708–716. https://doi.org/10.2138/am-1997-7-808 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 Frank C. Hawthorne, Giancarlo Della Ventura, Jean-Louis Robert, Mark D. Welch, Mati Raudsepp, David M. Jenkins; A Rietveld and infrared study of synthetic amphiboles along the potassium-richterite-tremolite join. American Mineralogist 1997;; 82 (7-8): 708–716. doi: https://doi.org/10.2138/am-1997-7-808 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Amphiboles were synthesized at 750° C, 1 kbar (H2O) for compositions at 20% intervals along the join potassium-richterite-tremolite. Structural variations, site occupancies, and modal analyses of the experimental products (amphibole + minor diopside, quartz, and enstatite) were characterized by Rietveld structure refinement, with final RBragg indices in the range 4–6%, and by infrared spectroscopy in the principal OH-stretching region. Amphibole compositions were determined by (1) site-scattering refinement for the A and M4 sites that are occupied by (K, □) (□ = vacancy) and (Na,Ca), respectively; and (2) mass-balance calculations involving the modal analysis and the nominal experimental product composition. These measurements agree within 1% absolute and show close agreement with electron-microprobe compositions for the two samples that we could analyze. Deviations from nominal amphibole composition are up to 19% absolute. The resulting relations between cell dimension and composition are linear. The major change in cell dimensions is a decrease of 0.25 Å in a with increasing tremolite component.The infrared spectra show two principal peaks at 3735 and 3675 cm–1, corresponding to the local arrangements MgMgMg-OH-AK (the Kr band) and MgMgMg-OH-A□ (the Tr band), respectively. The relative variation in peak intensity as a function of amphibole composition shows that the molar absorptivities of the two bands are significantly different. The ratio of the molar absorptivities for the two bands is 2.2. 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.