Assertion: opal | /r/CapableOf | occur as cement
Facets:
value: as cavity fillings
type: MANNER
value: as vein
type: LOCATION
value: in sandstones
type: LOCATION
value: as a replacement of wood
type: CAUSE
Source sentences:
text: Opal also occurs as nodules and masses, as cement in sandstones, as vein and cavity fillings, and as a replacement of wood.