When using a flint, you should remember that it is a forged and tempered product. As such it can be very strong, but at the same time it possesses a certain degree of brittleness. Remember how old wrought iron blades, though able to strike the enemy and puncture his armor or chain mail, would often betray their masters and break in the midst of battle. Similarly wrought flints can also break if used incorrectly or inappropriately. In the majority of cases when flints break, it occurs when they fall onto rocks or when someone tries to use one as a little hammer to split a piece of flint held in the palm of their hand. There's another important point that you need to know about firesteels (steel strikers). As with your favorite camping knife, you shouldn't heat your firesteel over a flame as you can remove its tempered quality, rendering it unable to make sparks.