Rock. Hard rock. Hard black rock.
Hard black rock from out a volcano.
You want lumps? Fall on this, get plenty big owies.
Usually sharp around the edges. Can be ornery if cornered but generally hangs out quietly in cliffs and in large beds underfoot.
Significant parts of the earth are made from basalt.
It used to be hot and runny.
Could be again some day.
Sleep with one eye open.
Source: How to talk in the woods.