Assertion: occurring hydrogen | /r/MadeOf | three isotopes
Facets:
value: naturally
type: MANNER
value: a minute trace
type: TEMPORAL
Source sentences:
text: Naturally occurring hydrogen consists of three isotopes: hydrogen-1, or protium, 99.985 percent; hydrogen-2, or deuterium (q.v.), 0.015 percent; and hydrogen-3, or tritium (q.v.), a minute trace.