Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Kinetics of Al-Si exchange in low and high quartz; calculation of Al diffusion coefficients

Rainer Pankrath and Otto W. Floerke
Kinetics of Al-Si exchange in low and high quartz; calculation of Al diffusion coefficients
European Journal of Mineralogy (August 1994) 6 (4): 435-457

Abstract

The non-uniform distribution of Al between the three symmetrically equivalent Si sites in low quartz is converted to a random distribution by dry or hydrothermal annealing at >> 400 degrees C due to Al-Si exchange. Rate equations for the Al-Si exchange are derived from experimental results; the kinetics of this exchange reaction are strongly influenced by whether the type of Si substitution is Al + Na ([AlO (sub 4) /Na] (super 4-) ) or Al + Li ([AlO (sub 4) /Li] (super 4-) ). In the second case, the activation energy of the Al-Si exchange in low quartz increases from 278 + or - 20 KJ/mole (dry, in air) to 400 + or - 25 KJ/mole at 100 MPa water P. A vacancy mechanism appears to be responsible for the Al-Si exchange; the calculated diffusion coefficients are estimated to be in the range 10 (super -24) to 10 (super -27) m (super 2) /s.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 6
Serial Issue: 4
Title: Kinetics of Al-Si exchange in low and high quartz; calculation of Al diffusion coefficients
Affiliation: Ruhr-Universitat Bochum, Bochum, Federal Republic of Germany
Pages: 435-457
Published: 199408
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 72
Accession Number: 1995-001803
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 4 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199501
Close Modal

or Create an Account

Close Modal
Close Modal