a piece of flint that is struck to light a fire
"He scraped his knife against the firestone until sparks flew and caught the dry tinder in seconds."
a sandstone that withstands intense heat; used to line fireplaces and furnaces and kilns
"The mason carefully selected high-quality firestone tiles to line the new furnace, ensuring it could safely withstand the intense heat of combustion."
Iron pyrites, formerly used for striking fire.
"The old miner struck the flint against a piece of firestone to light his lamp in the dark shaft."
A surname, from German.
"Many attendees at the local history fair were surprised to learn that Firestone was actually a common German surname before it became famous as a tire brand."