Assertion: tourmaline's variety | /r/HasProperty | rare
Facets:
value: especially
type: DEGREE
Source sentences:
text: Some varieties are especially rare and desirable, while others are almost as inexpensive as quartz.
text: Named after Czar Alexander, this variety of chrysoberyl is still a rare stone.
text: The blue tourmaline that has attracted the most attention is the rare paraiba variety that was first discovered in Brazil in 1989, and then later in Nigeria and Mozambique.