From the Dust

Mallet-head chisels are meant to be struck with a wooden mallet or soft metal dummy mallet.  The mushroom head of the chisel is hardened to the same degree as the cutting edge so as to transfer the entire force of the blow to the cutting edge striking the stone.

Mallet-head chisels are meant to be struck with a wooden mallet or soft metal dummy mallet.  The mushroom head of the chisel is hardened to the same degree as the cutting edge so as to transfer the entire force of the blow to the cutting edge striking the stone.