Perhaps no material is as closely tied to an era as marble is to the classical world. Marble is a pale, metamorphic rock derived from limestone, and though it has been used to make art since before written language, marble is most commonly associated with the heroic, idealized, beautiful sculptures of the human form created at the height of the Greek and Roman empires. The sculptors of these cultures not only developed an unparalleled naturallism in their rendering, but took advantage of marble’s most unique characteristic, a property called subsurface scattering. Marble’s composition leaves it slightly transparent, allowing light to sink into marble in the same way that it plays across and through human skin, giving human forms captured in marble an etherial, lifelike quality.
Reed Enger, "Marble, The stone that glows like human skin," in Obelisk Art History, Published January 23, 2015; last modified July 20, 2019, http://arthistoryproject.com/mediums/marble/.