Of all the decorative marbles that the Romans extracted from the length and breadth of their Empire – from Aquitaine to the Egyptian Desert, from African Numidia to the Propontis – none had such apparent popularity or was so widely employed throughout the Empire as marmor Carystium, which was available in such inexhaustible quantities in the foothills of Mount Ochi. Renaissance stone-workers called it Cipollino (‘onion-like') not so much because it has the appearance of sliced onion, but because the veins of mica which colour the calcareous body of the stone, cause it to be easily cut along the seams in the fashion of an onion.
Its illustrious career in Rome began, according to Cornelius Nepos (cited by Pliny, Nat. Hist. XXXVI 48) when it was introduced by Mamurra of Formiae, Julius Caesar's chief engineer in Gaul. It was extensively used in the Roman and Imperial Fora (Basilica Aemilia, Temple of Vespasian, the House of the Vestal Virgins, the Palace of Domitian, Forum of Trajan, Basilica of Maxentius etc.), its translucence and colour being preserved and refreshed by annual applications of a solution of chalk and milk. Amongst the largest monolithic columns of Carystian marble are those supporting the portico of the Temple of Antoninus and Faustina overlooking the Forum: they measure 40 Roman feet (11.9 m) and rise to 48 Rf (14.2 m) with their Corinthian capitals. The Romans also extracted asbestos (whose curious properties so fascinated them: see Strabo, Geog. X, 1.6) from these same hills.
Info: McGilchrist's Greek Islands
(From McGilchrist’s Greek Islands, © Nigel McGilchrist 2010, excerpted with his gracious permission. Click for the books)