Cerium is the most abundant rare-earth element. It ignites at a low temperature, and for this reason it is used in flints in the form of an alloy, ferrocerium, to strike the spark in this butane lighter.

Cerium is the most abundant rare-earth element. It ignites at a low temperature, and for this reason it is used in flints in the form of an alloy, ferrocerium, to strike the spark in this butane lighter.