Abbasid, temp. al-Mahdi, cast Fals, no mint or date, citing Ibrahim b. Salih and another unidentified official, 1.69g (SICA 2:1580). Fine, very rare.
Ibrahim b. Salih was governor of Egypt from 165-167h. The name of the official cited on the reverse is not clear, but it does not appear to be the name ('Asim b. Hafs) suggested by Nicol in SICA.
Estimate: £80-100