Assertion: opal | /r/HasProperty | classed as mineraloid
Facets:
value: because of its amorphous character
type: CAUSE
value: unlike crystalline forms of silica
type: OTHER
Source sentences:
text: Because of its amorphous character, it is classed as a mineraloid, unlike crystalline forms of silica, which are classed as minerals.
text: Because of its amorphous character, it is classed as a mineraloid, unlike the other crystalline forms of silica, which are classed as minerals.