firestone Meaning, Definition & Usage

  1. noun a piece of flint that is struck to light a fire
  2. noun a sandstone that withstands intense heat; used to line fireplaces and furnaces and kilns

WordNet

Fire"stone` noun
Etymology
AS. frstan flint; fr fire + stan stone.
Definitions
  1. Iron pyrites, formerly used for striking fire; also, a flint.
  2. A stone which will bear the heat of a furnace without injury; -- especially applied to the sandstone at the top of the upper greensand in the south of England, used for lining kilns and furnaces. Ure.

Webster 1913