ABBASID REVOLUTION: Anonymous, 744-751, AR dirham (2.81g), Marw, AH131, A-206.2, Klat-, struck by partisans of Abu Muslim ('Abd al-Rahman b. Muslim al-Balkhi) at Balkh AH130-132, Jurjan 130, Marw 130-131, and al-Rayy 131; this is the first example of type A-206.2, with 4 groups of triplets of dots in the outer obverse margin within the mint/date formula and Qur'an verse 42:23 in the inner margin; unique and of the highest rarity! VF, RRRR. Klat lists the type only for AH130 at Marw (his #604, several on CoinArchives), which switched to type #206.3, without the Qur'an verse 42:23 (only scarce for all years 131-133). In the 20 years since Klat published his standard reference for Umayyad dirhams, only two new types have been discovered, a lovely version for Sijistan 132 (two known, from New York Sale 2013 and ICA Auction 27 in 2016) and this piece of Marw 131.
Estimate: USD 4000 - 5000