Polysomatism and modules of gehlenite composition and structure in the Hanic phase (Ca5Al6MgSiO17)

I. Dódony, P. R. Buseck

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Discrete, well-ordered, single-phase crystals (the Hanic phase) form when powders the bulk composition of Ca5Al6MgSiO17 are allowed to react in the absence of a melt. If, on the other hand, either the powders or crystals of Ca5Al6MgSiO17 are molten and then cooled, complex intergrowths form. These intergrowths consist of modules having the composition and structure of Ca3Al4MgO10 and gehlenite (Ca2Al2SiO7), forming a polysomatic series in which the modules occur in varied proportions. High-resolution transmission electron microscope (HRTEM) images reveal the details of these intergrowths. Mass balance is achieved by the formation of this polysomatic series together with Mg-substituted mayenite (Ca12-xMgxAl14O33). The tetrahedral sheets in gehlenite have close structural similarities to those of Ca5Al6O14. Based on our HRTEM images, we hypothesize chemical substitutions between gehlenite and Ca5Al6O14, resulting in gehlenite-like modules that are depleted in Si and correspondingly enriched in Al and Ca.

Original languageEnglish (US)
Pages (from-to)428-434
Number of pages7
JournalPhysics and Chemistry of Minerals
Volume28
Issue number6
DOIs
StatePublished - Jan 1 2001
Externally publishedYes

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Keywords

  • Calcium-aluminates
  • Gehlenite
  • Polysomatism
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Geochemistry and Petrology

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