Assertion: mineral's crystal | /r/HasProperty | rare
Facets:
value: in nature
type: LOCATION
value: exceedingly
type: DEGREE
value: until the 19th century
type: TEMPORAL
value: quite
type: DEGREE
Source sentences:
text: Until the 19th century, large crystals of mica were quite rare and expensive as a result of the limited supply in Europe.
text: In nature, a perfect crystal is rare.
text: In nature, a perfect crystal is rare.
text: Crystals, even at the microscopic scale, are exceedingly rare.