cold chisel is a heavy duty type of chisel which is designed primarily
for masonry work.
Cold chisels are ideally suited to removing mortar from bricks,
or tapping though cement blocks and hollow terracotta bricks when
making an opening.
Cold chisels are designed to be used with a heavyweight metal hammer
to provide a strong striking blow. Over time the head of the cold
chisel will mushroom out due to the repeated hammer blows - this
is not a problem, just a sign of a well used cold chisel!