Compressibility of clinochlore to 8 GPa at 298 K and a comparison with micas

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doi: 10.1127/0935-1221/2002/0014-0561
Authors:Welch, Mark D.; Crichton, Wilson A.
Author Affiliations:Primary:
Natural History Museum, Department of Mineralogy, London, United Kingdom
European Synchrotron Radiation Facility, France
Volume Title:European Journal of Mineralogy
Source:European Journal of Mineralogy, 14(3), p.561-565. Publisher: Schweizerbart'sche Verlagsbuchhandlung (Nägele u. Obermiller), Stuttgart, Federal Republic of Germany. ISSN: 0935-1221
Publication Date:2002
Note:In English. 20 refs.; illus., incl. 2 tables
Summary:The equation of state of deuterated synthetic end-member C2/m clinochlore, Mg5Al(Si3Al)O10(OD)8, has been determined by synchrotron X-ray powder diffraction in the pressure range 0-7.7 GPa. The room-temperature bulk modulus K0 obtained from a fit of sixteen measurements to a second-order Birch-Murnaghan equation of state (K'0 = 4) is K0 = 81.0±0.5 GPa. Fitting to a third-order Birch-Murnaghan equation of state gives K0 = 83.1±1.7 GPa and K'0 = 3.3±0.6 and, within error, the two fits are indistinguishable over this pressure range. Axial moduli (K'0 = 4) for clinochlore are: K0a = 91(1) GPa, K0b = 89(1) GPa, K0c = 67(2) GPa. Comparison with published compressibilities for phlogopite, muscovite and phengite reveals that the micas are slightly less compressible along [100] and [010] than clinochlore, but micas are three times more compressible than clinochlore normal to the (001) structural layering. The very different compressibilities of micas and clinochlore normal to their polyhedral sheets indicates that the type of interlayer bonding has a major effect upon compressibility.
Sections:Physical properties of rocks and minerals
Subjects:Bulk modulus; Chlorite group; Clinochlore; Compressibility; Elastic constants; Equations of state; High pressure; High temperature; Mica group; Pressure; Sheet silicates; Silicates; Temperature; X-ray diffraction data
Abstract Numbers:02M/4754
Record ID:2002047657
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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