Eccentricity of hexagonal dislocation etch pits

Abstract

Dislocation etch pits with hexagonal outlines are revealed on calcite cleavages which have been etched with glacial acetic acid. The pits are symmetric with respect to the [110] direction, but their depth points do not coincide with the geometrical centres of planar etch pits and thus they are eccentric. For hexagonal etch pits the shifts and eccentricities lie along the [110] direction, unlike rhombic etch pits where the eccentricity lies along the [ 110 ] direction. The eccentricity in the hexagonal etch pits is explained on the basis of lateral reaction rates which are dependent on the concentration of the etchant.