Abrasive

An abrasive is a material or substance used to wear down or polish surfaces by friction. In ancient times, abrasives like sand, crushed stone, or pumice were used to smooth stone or metal surfaces, particularly for finishing sculptures or architectural elements. Given the context in which the tombs were carved at Hegra, it is assumed that the abrasives used to smooth the surface of some of the decorative elements were either sandstone itself or local sand.