Assertion: thorium | /r/ObjectUse | used as light source
Facets:
value: as an alloying material
type: MANNER
value: once commonly
type: TEMPORAL
value: in gas mantles
type: LOCATION
Source sentences:
text: Thorium was once commonly used as the light source in gas mantles and as an alloying material, but these applications have declined due to concerns about its radioactivity.