SG Heritage Dictionary

Firestone [Noun] Webster's Dictionary 1828

1. A fossil, the pyrite. [ See Pyrite .]

2. A kind of freestone which bears a high degree of heat.

Firestone [Noun] Webster's Dictionary 1913

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.