Constantine IV. (668-685 AD). Silver hexagram (6.52 gm). 

AR Hexagram Obv: Helmeted, cuirassed bust facing, holding spear over shoulder and shield.

Rev: Heraclius and Tiberius standing either side of a cross potent on ? 
and three steps. 669-674 (Constantinople).

SB 1169, DOC II 24, MIB III 66 

Used with permission of CNG coins, www.cngcoins.com, Nov. 2010