Optical Absorption Spectra of Clay Minerals

Samuel W. Karickhoff and George W. Bailey
Environmental Protection Agency, National Environmental Research Center—Corvallis, Southeast Environmental Research Laboratory Athens, Georgia 30601, U.S.A.

Abstract: A preliminary survey of electronic absorption spectra of clay minerals reveals the utility of u.v.-visible spectroscopy in the elucidation of structural, physical, and chemical properties of such systems. Spectra, which were obtained in the suspension, film, and single crystal states (where applicable), are interpreted in terms of iron-associated transitions. Microcrystalline clay minerals typically show Fe(III) in octahedral oxo-ligand geometry whereas mica-type minerals may show a range of iron species, including octahedral Fe(III), tetrahedral Fe(III), and octahedral Fe(II). Iron affects the local site geometry and in “high iron” minerals may dictate layer geometry and subsequently the crystalline form.

Clays and Clay Minerals; February 1973 v. 21; no. 1; p. 59-70; DOI: 10.1346/CCMN.1973.0210109
© 1973, The Clay Minerals Society
Clay Minerals Society (www.clays.org)