n. 燧石, 耐火石

Firestone \Fire"stone`\ (?; 110), n. [AS. f[=y]rst[=a]n flint;
f[=y]r fire + st[=a]n stone.]
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.