In the so-called ‘Ninfeo dell'Ercole’, located along the cardo maximus of Leptis Magna, there is a column made from the red marble that the Romans called Marmor Iassense or Carium, after the ancient town of Iasos in Caria (Asia Minor), where quarries have recently been identified. Although this marble began to be exploited probably in Hellenistic times, most experts believe that its extensive trade started only in the third century AD, and increased in the followings centuries, when its occurrence became conspicuous in Asia Minor and in other eastern and central Mediterranean regions. The fact that this column in Leptis Magna belongs to a monument dating from the second half of the second century AD now provides positive evidence for the circulation of marble Iassense in earlier times. Moreover, particularly interesting is the peculiar composition of the stone, in which both the veined and the breccia-like varieties are present. This feature is rather uncommon and particularly significant, for the two types have usually been considered quite distinct. Recent investigations conducted in the quarries of Iasos, however, have revealed that the two varieties can coexist in the same outcrops.