'''Actinium''' is a very rare [[radioactive]] chemical [[element]]. It is silvery-white and glows blue in the dark. <ref>[[Encylopaedia Britannica]] online, [http://www.britannica.com/eb/article-9003601/actinium ''Actinium'']</ref> | '''Actinium''' is a very rare [[radioactive]] chemical [[element]]. It is silvery-white and glows blue in the dark. <ref>[[Encylopaedia Britannica]] online, [http://www.britannica.com/eb/article-9003601/actinium ''Actinium'']</ref> |