Assertion: protactinium's isotope | /r/CapableOf | exist on the earth
Facets:
value: primordially
type: DEGREE
Source sentences:
text: The modern theory of the atomic nucleus does not suggest a long-lived isotope of dubnium, but claims were made in the past that unknown isotopes of superheavy elements existed primordially on the Earth: for example, such a claim was raised for108 of a half-life of 400 to 500 million years in 1963or122 of a half-life of over 100 million years in 2009;neither claim gained acceptance. ^