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Webster 1913 Edition

Noun.

(Min.)

A siliceous stone, a variety of quartz, closely resembling flint, but more brittle; – called also

chert

Noun.

A siliceous stone, a subspecies of quartz. It is divided by Jameson into splintery, conchoidal, and wood-stone. [See Chert.]

hornstone ‎(countable and uncountable, plural hornstones)