Coal
Hope nobody is hobophobic because this guy is just impossible to wash! Your hands will stay dirty forever after touching him...
Coal was raised on rock and of course he's not as fancy and effeminate as his older brother, Diamond, who is basically just Coal that underwent millions of years of tight-lacing in his life... But still, Coal is more useful to us simple humans. And a lot, a lot cheaper! You can burn it in the oven, make torches with it if you have sticks, or even make tools for drawing, among other things!
Coal is not as hard as his effete brother, but unlike the ever cold Diamond, Coal can be super hot and keep your evening warm!