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(K,Sr)-feldspar solid solutions; the volume behaviour of heterovalent feldspars

Herbert Kroll, Alexej R. Kotelnikov, Joerg Goettlicher and Elena V. Valyashko
(K,Sr)-feldspar solid solutions; the volume behaviour of heterovalent feldspars
European Journal of Mineralogy (June 1995) 7 (3): 489-499


A series of (K,Sr)-feldspars was synthesized hydrothermally by cation exchange according to the reaction: 2 KAlSi (sub 3) O (sub 8) + SrCl (sub 2) = SrAl (sub 2) Si (sub 2) O (sub 8) + 2 KCl. The distribution of K and Sr between feldspar and fluid is non-ideal. The excess free energy of mixing has been modelled by an asymmetric Margules expression. The behaviour of the cell parameters is similar to that of the (K,Ca)-feldspars, including excess volumes which are negative. This is in contrast to other binary feldspar solid solutions, where excess volumes are either close to zero (Na,Ca-feldspars) or are positive (Na,Sr-, Na,Ba-, K,Ba-feldspars). In an attempt to to rationalize the volume behaviour of heterovalent feldspars, the misfit strain energy model of Christian (1981) was used; this showed that the experimental data and model predictions qualitatively agree. A positive excess volume results when both the molar volume and the bulk modulus in one end-member are larger than in the other one, whereas a negative excess volume is found when in one end-member the molar volume is larger, but the bulk modulus is smaller than in the other end-member.

ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 3
Title: (K,Sr)-feldspar solid solutions; the volume behaviour of heterovalent feldspars
Affiliation: Westfaelische Wilhelms-Universitaet, Institut fuer Mineralogie, Munster, Federal Republic of Germany
Pages: 489-499
Published: 199506
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 30
Accession Number: 1995-041693
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables
Secondary Affiliation: Russian Academy of Science, RUS, Russian Federation
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199515
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