NH4F Treatment Research Articles

Occurrence of Chlorite‐Like Intergrade Clay Minerals in Coastal Plain, Piedmont, and Mountain Soils of North Carolina

AbstractSoils of the Coastal Plain, Piedmont, and Mountain regions of North Carolina were examined for the occurrence of chlorite‐like intergrade clay minerals. The intergrade clay minerals were found to be very common constitutents of soils examined, ranging in occurrence from trace to major amounts. Degree of interlayering, as estimated from response of clays to acid NH4F treatment, was related to position of the clay in the profile, usually, though not always, decreasing with depth. The amount of 3‐layer clay, as estimated by X‐ray diffraction, was greatest in the surface horizons and decreased with depth. For soils formed on similar parent material, 3‐layer clays from well‐drained, highly oxidized soils were usually more difficult to collapse than those from less oxidized soils. Chemical and mineralogical studies suggest that the intergrade clay minerals originated from mica precursors.