ISLAMIC, 'Abbasid Caliphate. Al-Ma'mun, AH 193-218 / AD 809-833. Dirham (Silver, 25 mm, 3.00 g, 9 h), citing Dhu'l Riyasatayn (holder of the two ministries) al-Fadl, the vizier of the caliph al-Ma'mun, al-Basra, AH 199 = AD 814/5. SICA III, 716. Rare. Struck from a somewhat worn reverse die, otherwise, very fine.