Crossword Genius

Form of chalcedony (4)

Ross

I believe the answer is:

onyx

'form of chalcedony' is the definition.
(I've seen this before)

This is the entire clue.

(Other definitions for onyx that I've seen before include "Semi-precious variety of agate" , "Type of agate" , "Marbled stone with layers of colours" , "Black variety of quartz" , "Smooth stone with bands of colour" .)

I've seen this clue in The Sunday Times and The 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.