Two independent refinements of the structure of paracelsian, BaAl2Si2O8

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Authors:Chiari, G.; Gazzoni, G.; Craig, James R.; Gibbs, G. V.; Louisnathan, S. J.
Author Affiliations:Primary:
Dip. Sci. Terra, Turin, Italy
Va. Polytech. Inst. and State Univ., United States
Volume Title:American Mineralogist
Source:American Mineralogist, 70(9-10), p.969-974. Publisher: Mineralogical Society of America, Washington, DC, United States. ISSN: 0003-004X
Publication Date:1985
Note:In English. 10 refs.; illus. incl. 6 tables
Summary:Two independent refinements of natural paracelsian, using different crystals from Benallt mine, Caernarvonshire (N Wales), yielded comparable R values (R = 3.47%, Rw = 2.95% and R = 3.5%, Rw = 4.3%). Unit-cell parameters and atomic coordinates are significantly different in the two refinements, but the Ba polyhedra distances and the O-T-O and T-O-T angles are very similar. Although the grand mean T-O values are equal, the tetrahedra show systematic variations which are ascribed to differences in the degree of Al-Si disorder. [J.A.Z.]
Subjects:Barium feldspar; Cell dimensions; Crystal structure; Feldspar group; Framework silicates; Mineral data; Mineralogy; Minerals; Natural materials; Paracelsian; Refinement; Silicates; Europe; Great Britain; United Kingdom; Wales; Western Europe; Benallt Mine; Carnarvonshire; Northwestern Wales
Coordinates:N523000 N532000 W0034000 W0043000
Abstract Numbers:86M/1425
Record ID:1986017787
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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