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Acid Dissolution of Hematites of Different Morphologies

Published online by Cambridge University Press:  09 July 2018

R. M. Cornell  and
R. Giovanoli
R. M. Cornell
Affiliation:
University of Berne, Laboratory for Electron Microscopy, Freiestrasse 3, 3000 Berne 9, Switzerland
R. Giovanoli
Affiliation:
University of Berne, Laboratory for Electron Microscopy, Freiestrasse 3, 3000 Berne 9, Switzerland
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Abstract

Dissolution in HCl of hematite particles with different morphologies led to sigmoidal dissolution vs. time curves. The rate of dissolution was directly proportional to the sample surface area and independent of crystal morphology. Hematites produced by heating goethite at 600 or 800~ dissolved more rapidly per unit area than did hematites grown from solution. TEM showed that some platy crystals developed central holes after prolonged acid attack; the hole formation was attributed to enhanced dissolution at screw dislocations present on the (001) faces of the crystals. Except where particularly susceptible regions involving strained areas or dislocations were present, there appeared to be no preferential acid attack at any particular crystal face. The original morphology was usually maintained during the reaction.

Type
Research Article
Information
Clay Minerals , Volume 28 , Issue 2 , June 1993 , pp. 223 - 232
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1993

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