Assertion: pm | /r/HasProperty | rare
Facets:
value: vanishingly
type: DEGREE
value: extremely
type: DEGREE
Source sentences:
text: Promethium is a lanthanide and rare earth metal Color: silvery-white Atomic weight: (145), no stable isotopes State:
text: Promethium is an extremely rare element and only 500-600g of promethium is naturally present in the earth
text: (Ln deonotes a mixture of all the lanthanoids except promethium which is vanishingly rare) and the third is a fluoride carbonate LnCO 3 F. Lanthanoids with even atomic numbers are more common.
text: Promethium is a lanthanide and rare earth metal Color: silvery-white Atomic weight: (145), no stable isotopes State: