Geologists

The trick is to bang your rocks into other rocks.

Particularly not when they're used to hitting rocks with them...

NoNoNoNoNo.  You misunderstand.  People only think we use the hammers on rocks.  No, a true geologist uses their head, and saves the hammer for later... ;-) --Jumlian

The ImperialCollege? (London, aka, RoyalSchoolofMines?) handbook for field safety legendarily had something like the the following advice in it:

Section XYZ.  Working alone in the field.

In case of attack in the field, we have found the following advice useful:

YOU ARE CARRYING A LARGE STEEL HAMMER.  THIS MAKES A GOOD WEAPON.