Assertion: opal | /r/HasProperty | rare
Facets:
value: very
type: DEGREE
value: in antiquity
type: TEMPORAL
value: by the way
type: OTHER
Source sentences:
text: Opal was rare and very valuable in antiquity.
text: By the way, opals with blue spots are considered very rare and expensive.
text: Opals are a rare semi-precious gemstone so the price should reflect this.
text: Opal was rare and very valuable in antiquity.
text: Opals that have a predominantly red colour are very rare as they only occur where larger silica spheres were deposited.