Instead of knapping like flint/obsidian, with slate you grind. I just picked up a new grindstone and this was its first project actually. And when I say "pick up", I mean exactly that, it was a likely-looking rock I saw while walking around. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> Pretty too, lots of mica in it. Once you grind the major shape out, you do the final sharpening and polishing with another piece of slate. I'm a little dissatisfied with how sharp the edge (doesn't) get doing this, I think there must be a trick to getting a better edge. Thinking bone maybe since it's fairly hard but fine grained.