The location of H in the high-pressure synthetic Al2SiO4 (OH)2 topaz analogue

P. A. Northrup, K. Leinenweber, J. B. Parise

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


The positions of H in Al2SiO4(OH)2, the fully hydrated high-pressure synthetic analogue of topaz have been determined from single-crystal XRD. Two nonequivalent H positions, approximately 2.4 Å apart, were located. The H sites are significantly displaced from the single one found in natural OH-bearing fluor-topaz and violate the mirror plane of space group Pbnm, at least locally. Each H is associated with three O atoms in an irregular trifurcated H-bond arrangement. These results provide an explanation for observations of split OH-stretching bands in infrared spectra, as well as for the uniform dilatation observed for both the [6]Al and [4]Si polyhedra relative to those in fluor-topaz. -from Authors

Original languageEnglish (US)
Pages (from-to)401-404
Number of pages4
JournalAmerican Mineralogist
Issue number3-4
StatePublished - Jan 1 1994
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology


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