FIRESTONE

firestone. Firestone, n. pyrite, a compound of sulphur and a metal

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Fire″stone′ (?; 110), n. [[AS. fȳrstān flint; fȳr fire + stān stone.]] 1. 1. Iron pyrites, formerly used for striking fire; also, a flint.
2. 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.