Case hardening takes place in various types of rocks, being notable in porous ones, for example sandstone, quartzite and volcanic ash. The cement effect by silica observed in sandstone and quartzite is prominent.Campbell, S.W. 1999. Chemical weathering associated with tafoni at Papago Park, Central Arizona. Earth Surface Process and Landforms, 24, 271-278 Sandstone from the Valley of Fire, Nevada, is usually cemented by calcite but the calcium borate mineral, colemanite, has also been found in some cases to act as a cement.Conca, J.L. and Rossman, G.R. 1982. Case hardening of sandstone. Geology, 10, 520-523 A similar phenomenon is observed in felsic alkaline rocks, such as nepheline syenite, alkaline syenite, phonolite, and trachyte, because of weathering vulnerability of nepheline and alkaline feldspar.Motoki, A., Soares, R., Lobato, M., Sichel, S.E., Aires, J.R. 2007. Feições intempéricas em rochas alcalinas félsicas de Nova Iguaçu, RJ. Revista Escola de Minas, 60-3, 451-548 The case hardening on trachytic clasts of volcanic breccia shows peculiar fabrics.
