Flinty
FLINT'Y, adjective
1. Consisting of flint; as a flinty rock.
2. Like flint; very hard, not impressible; as a flinty heart.
3. Cruel; unmerciful; inexorable.
4. Full of flint stones, as flinty ground.
Flinty-slate, a mineral of two kinds, the common and the Lydian stone.