Enter a clue or pattern or both:
The Clue
Fine-grained rock (5 letter answer)
The Answer
CHERT
Tags
Notes
The answer CHERT is so rare that it appears less than once every 2500 puzzles.
Related Clues
Quartz
Flintlike rock
Definition
CHERT as a noun:
1. variety of silica containing microcrystalline quartz