Assertion: onyx | /r/HasProperty | hard rock
Facets:
value: much
type: DEGREE
value: like quartz crystals
type: OTHER
Source sentences:
text: Like quartz crystals, onyx is a hard rock, rated in the Mohs scale of hardness at 6 to 7.
text: Onyx is a much harder stone composed of chalcedony with straight bands of color instead of the curved forms typical of agate.