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Crystal-structure analysis of a birefringent andradite

Kathleen J. Kingma and James W. Downs
Crystal-structure analysis of a birefringent andradite
American Mineralogist (December 1989) 74 (11-12): 1307-1316


The crystal structure of a non-cubic garnet of composition And (sub 94) Gr (sub 5) Spess (sub 1) was refined from single-crystal XRD intensities to R (sub w) = 2.4% for 3145 observations unique under Laue group 1. Although the unit cell is metrically cubic, with a 12.048(1) Angstrom, the space group for this optically anisotropic garnet is found to be I1, a subgroup of Ia3d. Partial long-range ordering of Fe (super 3+) and Al over the eight symmetrically unique octahedral sites of the I1 structure is found to be significant and is cited as a possible origin for the observed optical anisotropy. [Authors' abstract]

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 74
Serial Issue: 11-12
Title: Crystal-structure analysis of a birefringent andradite
Affiliation: Ohio State Univ., Dep. Geol. and Mineral., Columbus, OH, United States
Pages: 1307-1316
Published: 198912
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 33
Accession Number: 1990-023257
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 8 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 1990
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