Quartz-filled rock (5)
I believe the answer is:
geode
(Other definitions for geode that I've seen before include "Small rock cavity" , "Crystal-lined cavity in rock" , "Druse" .)
I've seen this clue in The New York Times.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free.
Check out my app
or
learn more
about the Crossword Genius project.