Blue andalusite from Ottré, Venn-Stavelot Massif, Belgium; a new example of intervalence charge-transfer in the aluminium silicate polymorphs

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Authors:Langer, K.; Halenius, E.; Fransolet, A. M.
Author Affiliations:Primary:
Univ. Liège, Inst. Minéral., Liège 4000, Belgium
Volume Title:Bulletin de Minéralogie
Source:Bulletin de Minéralogie, 107(5), p.587-596. Publisher: Masson, Paris, France. ISSN: 0180-9210
Publication Date:1984
Note:In English with French summary. 1 p. refs.; illus. incl. 7 anal., 3 tables, geol. sketch map
Summary:Blue andalusite occurs rimmed by pyrophyllite and kaolinite in quartz veins in metapelitic country rocks of the Venn-Stavelot massif affected by low-grade metamorphism. It has alpha 1.637, beta 1.642, gamma 1.647, 2Valpha 88° with a 7.791, b 7.897, c 5.556 A. Microprobe analyses show that Fe2O3 is in the range 0.86-0.46%; P2O5 ranges from 0.04 in the colourless parts of the crystals to 0.31% in the blue parts. The formula for the blue part is 219(Al1.959Fe3+0.012Fe2+0.006)Si1.002P0.006O5; the substitution is inferred to be Si4+ + M3+ = P5+ + Fe2+, giving the incorporation of P5+ in tetrahedral sites. The polarized single-crystal absorption spectra are given. [R.A.H.]
Subjects:Andalusite; Ferric iron; Ferrous iron; Geochemistry; Iron; Metals; Mineralogy; Minerals; Nesosilicates; Orthosilicates; Phosphorus; Silicates; Substitution; Belgium; Europe; Stavelot-Venn Massif; Western Europe; Charge-transfer; Ottre
Abstract Numbers:85M/1832
Record ID:1987011816
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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