Stone hard 10000 to 9483 -- 9665 Gres ---- to 8767 -- 9273 Lead ---- to 7671 -- 8590 Tin ---- to 7424 -- 6666 Stone soft ---- to 7327 -- 7959 Clay ---- to 7272 -- 7213 Antimony ---- to 6279 -- 8333 Oker ---- to 6136 -- 6393 Chalk ---- to 5581 -- 6333 Wood ---- to 2500 -- 3279