A multidisciplinary approach to investigate weathering processes affecting gneissic rocks (Calabria, southern Italy)

•An interdisciplinary research of weathering profiles was performed.•Weathered profiles are complex and reach a thickness of 70 m.•Physical changes coupled to chemical variations are described in detail.•The XRD patterns show high content of clay minerals (mixed-layer minerals).•The more weathered samples show higher CIA, CIW, PIA and CIW’ values.