Magnetic Behavior and Infrared Spectra of Jarosite, Basic Iron Sulfate,
and Their Chromate Analogs

Dana A Powers1, George R. Rossman1, Harvey J. Schugar2, Harry B. Gray1

  1Division of Geological and Planetary Sciences
California Institute of Technology
Pasadena, CA  91125

2Department of Chemistry
Rutgers University
New Brunswick, NJ 08903


The magnetic behavior and infrared spectroscopic features of KFe3(SO4)2(OH)6, (jarosite), (H3O)Fe3(SO4)2(OH)6, (hydronium jarosite), KFe3(CrO4)2(OH)6,, Fe(OH)SO4 (basic iron sulfate) and Fe(OH)CrO4, (basic iron chromate) are reported. Spectroscopic data are in accord with X-ray data which show that KFe3(SO4)2(OH)6, (H3O)Fe3(SO4)2(OH)6, KFe3(CrO4)2(OH)6, are isostructural with KAl3(SO4)2(OH)6 (akunite). All the species exhibit negative deviations from Curie-Weiss behavior over the temperature range 300-76 K. The compounds KFe3(CrO4)2(OH)6 and Fe(OH)CrO4 undergo ferrimagnetic transitions at 73 and 71 K, respectively. Maxima occur in the susceptibilities of KFe3(SO4)2(OH)66 and (H3O)Fe3(SO4)2(OH)6 at 45 and 50 K.


Molar magnetic susceptibility vs temperature for the basic iron suphates and chromates.

last updated: 26-Jul-2023