Assertion: actinium's symbol | /r/ObjectUse | used for the element
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Source sentences:
text: In the decades after French scientist Antoine Lavoisier developed the first modern definition of chemical elements, it was believed that earths could be reduced to their elements, meaning that the discovery of a new earth was equivalent to the discovery of the element within, which in this case would have been yttrium.[n 2] Until the early 1920s, the chemical symbol "Yt" was used for the element, after which "Y" came into common use.