Crystal structure and iron topochemistry of erionite-K from Rome, Oregon, USA


Ballirano P., Andreozzi G. B., DOĞAN M., DOĞAN A. Ü.

AMERICAN MINERALOGIST, vol.94, pp.1262-1270, 2009 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 94
  • Publication Date: 2009
  • Doi Number: 10.2138/am.2009.3163
  • Journal Name: AMERICAN MINERALOGIST
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1262-1270
  • Hacettepe University Affiliated: Yes

Abstract

A complete crystal-chemical characterization of erionite-K from Rome, Oregon, was obtained by combining field emission scanning electron microscopy, laboratory parallel-beam transmission powder diffraction, and Fe-57 Mossbauer spectroscopy. Rietveld refinement results evidenced that the most striking difference in comparison with the structure of erionite-Ca is significant K at a K2 site ((1)/(2), 0, 0), which is empty in erionite-Ca. In addition, site Ca1 shows low occupancy and Ca3 is vacant. The oxidation and coordination state of Fe, whose occurrence was revealed by chemical analysis, have been clarified by exploiting room- and low-temperature Fe-57 Mossbauer spectroscopy. The majority of Fe (95%) was attributed to Fe3+-bearing, superparamagnetic, oxide-like nanoparticles with dimensions between 1 and 9 nm, and the remaining 5% was attributed to hematite particles with size >= 10 nm, both located on the crystal surface.