Porphyry was quarried by the Romans from Mons Porphyrites in Egypt throughout the 1st-5th Century A.D. The material was much prized from the Roman period onwards and many early sculptures were recarved in later times, adding to the difficulty in accurately dating porphyry sculptures. For another porphyry basin, cf. Exhibition catalogue, In Pursuit of the Absolute: Art of the Ancient World from the George Ortiz Collection, Royal Academy of Arts, London, 1994, no. 241. Also, cf. R. Delbrueck, Antike Porphyrwerke, Berlin and Leipzig, 1932; and Radiance in Stone: Sculptures in Colored Marble from the Museo Nazionale Romano, 1989, for porphyry and its use in antiquity