Assertion: zircon's form | /r/HasProperty | rare
Facets:
Source sentences:
text: Because the natural form of cubic zirconia is so rare, all cubic zirconia used in jewelry has been synthesized, or created by humans.
text: Its most naturally occurring form, with a monoclinic crystalline structure, is the rare mineral, baddeleyite.
text: Because the natural form of cubic zirconia is so rare, all cubic zirconia used in jewelry has been synthesized, or created by humans.