Assertion: natural lithium | /r/MadeOf | about 7.5% lithium-6
Facets:
Source sentences:
text: Natural lithium contains about 7.5% lithium-6 from which large amounts of lithium-6 have been produced by isotope separation for use in nuclear weapons.
text: Natural lithium contains about 7.5 percent lithium-6, with the rest being lithium-7.