Pounamu is not a stone that can be hammered into shape. Well if you tried it wouldn't be with much precision at all. It is 1.5 times harder than tonson steal and therefore was valued for its density and toughness and its ability to hold a sharp edge. Māori found that in order to shape this stone they had to grind it. However, before this could be done had to create a whole stone working technology in order to cut it and then another to makes holes in it.
I still stand in awe at museums around Aotearoa when looking at sheer scale or effort and labour went into carving greenstone into tools, weapons and jewellery compared to the motorised diamond blades, grinders and drills we used in our workshop today. However, I still stand in awe watching my old man carve, he makes it look easy, but in fact its still bloody hard.