The saponite examined Occurs as two 0.1 in thick layers in a Pliocene sequence consisting of dolomite and dolomitic marl. To characterize this material, mineralogical and structural analyses (XRD, SEM and FTIR), thermal analyses (DTA, TG) and chemical analyses (ICP-ES) were performed. From XRD patterns of randomly-oriented powder samples, the first basal reflection appears as an asymmetric and broad peak with d(001) values varying between 16.55 and 17.32 angstrom. In oriented and air-dried samples, this reflection Occurs between 14.45 and 16.42 angstrom and is fairly symmetrical with FWHM of 2.7 degrees 20. Oriented and ethylene glycol-solvated samples produce a rational series of basal reflections, where 001 occurs at similar to 17.8 angstrom as an intense, narrow (1.1 degrees 20) and fairly symmetrical reflection. Upon solvation with glycerol, the 001 reflection shifts to similar to 18.7 angstrom.