Proper Use:
Bricklayers’ hammers are designed for setting and cutting (splitting) bricks, masonry tile and concrete blocks, and for chipping mortar from bricks.
Mis-Use/Abuse:
Never use a brick hammer to strike other steel tools of any type, or to drive hardened nails. The striking face or blade may chip, possibly resulting in eye or other serious injury.
Source: Hand Tools Institute, Hand Tool Use and Selection Chart