Reversible axe on adze with greenstone blade, North Papua, c 2000 BC.

This primitive hand axe has a greenstone blade that is tied to the handle by gras rope. Sharpened greenstone is a good material for cutting and chopping. Discovered in Astrolabe Bay, North Papua, the axe's right-angled design maximised the force its users could bring to bear on an object. This type of axe is still used for general woodwork.