Assertion: opal | /r/HasProperty | about same hardness
Facets:
value: as glass
type: OTHER
value: on the hardness scale
type: OTHER
Source sentences:
text: Opal is about the same hardness (5 to 6.5 on the hardness scale) an amethyst and jade yet you seldom hear of them fracturing.
text: Opals are about the same hardness as glass, so imagine you’re wearing a piece of glass