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Synthesis, properties and stability of Al (sub 3) Si (sub 2) O (sub 7) (OH) (sub 3) (phase Pi), a hydrous high-pressure phase in the system Al (sub 2) O (sub 3) -SiO (sub 2) H (sub 2) O (ASH)

Bernd Wunder, Olaf Medenbach, Werner Krause and Werner Schreyer
Synthesis, properties and stability of Al (sub 3) Si (sub 2) O (sub 7) (OH) (sub 3) (phase Pi), a hydrous high-pressure phase in the system Al (sub 2) O (sub 3) -SiO (sub 2) H (sub 2) O (ASH)
European Journal of Mineralogy (August 1993) 5 (4): 637-649

Abstract

A crystalline phase with composition Al (sub 3) Si (sub 2) O (sub 7) (OH) (sub 3) , here called Pi, has been synthesized at 40-55 kbar and 500-650 degrees C from gels of various compositions. Phase Pi forms euhedral triclinic crystals elongated [0.0], with 26 pedial faces; a 6.0885, b 7.2832, c 7.7234 Angstrom, alpha 115.71 degrees, beta 88.85 degrees, gamma 92.89 degrees, space group P1, Z = 2; alpha 1.665, beta 1.681, gamma 1.698, 2V (sub alpha) 86 degrees . Heating at 530 degrees C, 1 atm, leads to the breakdown of Pi into an as yet unidentified metastable phase. The low-P limit for phase Pi is near 22 kbar, at approx 430 degrees C. In nature, phase Pi may form in cold subduction zones at depths > approx 70 km.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 5
Serial Issue: 4
Title: Synthesis, properties and stability of Al (sub 3) Si (sub 2) O (sub 7) (OH) (sub 3) (phase Pi), a hydrous high-pressure phase in the system Al (sub 2) O (sub 3) -SiO (sub 2) H (sub 2) O (ASH)
Affiliation: Institut fuer Mineralogie, Research Group on High Pressure Metamorphism, Bochum, Federal Republic of Germany
Pages: 637-649
Published: 199308
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 20
Accession Number: 1993-023684
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
Secondary Affiliation: Henriette-Lott-Weg, DEU, Federal Republic of Germany
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 1993
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