Assertion: opal | /r/HasProperty | mineraloid
Facets:
Source sentences:
text: Therefore opal is a "mineraloid" rather than a "mineral.
text: Opal is considered a mineraloid and has no crystal structure.
text: Opals are not actually crystals; they are instead mineraloids as they lack the necessary microstructure to be called a crystalline.
text: Opal is considered a mineraloid because this structure is not truly crystalline.