5th-4th centuries B.C. Æ aes formatum. An aes formatum bronze axe, 160.8 g, 86 mm, rough green patina. Bronze axe heads were used for exchange across Europe even before 1000 B.C. This complete bronze axe head dates much later, ca. 5th - 4th centuries B.C. It was never used to cut wood, but was cast to serve as currency..