Another important property of flint is its ability to generate sparks of hot material when it is struck against steel. This property allows flint to be used as a fire-starter. Skilled people can use a piece of flint, a piece of steel, and a little tinder to quickly start a fire.

Early firearms, such as a flintlock, had a piece of flint attached to a spring-loaded hammer that was released when the trigger was pulled. The hammer struck a piece of steel known as a “frizzen” to create a shower of sparks that ignited a small pan of powder. That touched off the primary charge which exploded to propel the ball down the barrel.