Assertion: thorium | /r/HasProperty | occurrence
Facets:
value: naturally
type: MANNER
Source sentences:
text: Thorium: occurrences, geological deposits and resources, by F.H.Barthel & H.Tulsidas,
text: Although thorium (a naturally occurring substance) cannot be used to fuel a nuclear reactor, it can be mixed with a nuclear fuel like uranium-233 (a man-made substance) which can be used to fuel a reactor.