Assertion: occurring erbium | /r/AtLocation | percentage
Facets:
Source sentences:
text: Naturally occurring erbium is a mixture of six isotopes and they are found in the percentages shown: 162Er (0.1%), 164Er (1.6%), 166Er (33.6%), 167Er (22.9%), 168Er (26.8%) and 170Er (14.9%).