Ferrocerium is a man-made metallic material that has the ability to give off a large number of hot sparks when scraped against a rough surface, such as ridged steel. It is also commonly called ferro rod and most commonly of all, mistakenly, flint (particularly in cigarette lighters). As tinder-igniting campfire starter rods it is sold under such trade names as Blastmatch, Fire Steel, and Metal-Match for survivalists and bushcraft hobbyists. Even some manufacturers and resellers mistakenly call them “magnesium” rods. Ferrocerium rods works equally well when wet or dry.
To use a ferrocium rod simply run a blade down the rod and a shower of sparks will fly towards the tinder.
Practice at different speeds and pressure to see what works best for you.