Diamond has perfect cleavage in four directions. If you want a mineral that you can really pound on without it breaking, you want nephrite. The Maori made war

Diamond has perfect cleavage in four directions. If you want a mineral that you can really pound on without it breaking, you want nephrite. The Maori made war clubs out of it. Bring a diamond to a nephrite fight, and you're going to end up in the stewpot. If you need hardness and toughness, corundum is what you want.