• journal_title：American Mineralogist
• Contributor：Paolo Ballirano ; Giovanni B. Andreozzi ; Meral Dogan ; A. Umran Dogan
• Publisher：Mineralogical Society of America
• Date：2009-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2009.3163
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：94
• issue：8-9
• firstpage：1262
• section：Articles

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 ⁵⁷Fe Mössbauer 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(½, 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 ⁵⁷Fe Mössbauer 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.