Thread: What actually is Hardness in natural stones, and how it affects sharpening

This is a very complex subject. How well the stone cuts is dependent on so many things. The minerals the rock is comprised of, the kind of rock, the density, the particle size and shape, the mix of minerals in the rock and how they are mixed, and a host of others. Remember that running water is the best cutting force there is. It formed the Grand Canyon and can polish a rock to a mirror effect.