Aluminium Interlayers in Soil Clay Minerals, Montmorillonite and Vermiculite

Abstract

IN the past few years, some workers^1–3 have described the presence in soils of a vermiculite-like clay mineral with a 14 A. basal reflexion, showing a behaviour intermediate between that of vermiculite and chlorite when subjected to the usual procedures for characterization of clay minerals. This was attributed to aluminium in interlayer positions. Tamura⁴, of this laboratory, expanded this mineral by removing the interlayer aluminium with sodium citrate followed by saturation with calcium and solvation in glycerol. He thus showed the montmorillonitic nature of this mineral, which is widely distributed in the Holyoke and Wethersfield soils of the north-eastern United States. Considerable quantities of mineral with a stable 14 A. basal spacing occur in Hartford, Charlton and Gloucester soils in Connecticut. Interlayer aluminium may contribute to the low cation-exchange capacity, toxicity of aluminium and fixation of phosphate so commonly encountered in these soils.