Weathering of Glauconites: Reversal of the Glauconitization Process in a Soil Profile in Western France

C. Courbe, A. Meunier and B. Velde*
Laboratoire de Pédologie de l'Université de Poitiers, E.R.A. no 220 du C.N.R.S., 40 avenue du Recteur Pineau, 86022 Poitiers Cédex
* Laboratoire de Pétrographie de l'Université de Paris VI, 4 Place Jussieu 75230 Paris Cédex 05, France

Abstract: Polarizing microscope, electron microprobe and X-ray diffraction examination of minerals in a soil profile developed on a glauconite sand indicate that destabilization of glauconite can be a progressive process which appears to be the reverse of glauconitization. Glauconite in these soils appears to be destabilized into a mixed-layer glauconite-nontronite phase, which crystallizes as a plasma mineral. This material in turn is transformed into smectite + kaolinite + oxides. Loss of K and Fe is evident in whole rock as well as microprobe analyses of the samples. Thus glauconite can lose both Fe and K to aqueous solution during weathering, leaving aluminous clay minerals in the soil.

Clay Minerals; September 1981 v. 16; no. 3; p. 231-243; DOI: 10.1180/claymin.1981.016.3.02
© 1981, The Mineralogical Society
Mineralogical Society (www.minersoc.org)