Watch List notes:

ABBASID: al-Ma'mun, 810-833, AR heavy weight dirham (4.20g), Fars, AH203, A-224H, citing 'Ali b. Musa al-Rida, recognized as heir by al-Ma'mun, representing al-Ma'mun's ultimately failed attempt to establish peace and cooperation between the Sunni and Shi'a branches of Islam; also citing the vizier Dhu'l-Ri'asatayn, excellent strike, VF to EF, RRR. Extremely rare mint for this type, with none on either CoinArchives or Zeno.

Estimate: 1,000-1,500 USD