D defs.my
Entry 1 sense Webster, 1913

Hornstone

· Horn·stone · IPA
01 n. A siliceous stone, a variety of quartz, closely resembling flint, but more brittle; -- called also chert.
  1. 1.
    A siliceous stone, a variety of quartz, closely resembling flint, but more brittle; -- called also chert.(Min.) Also: chert