The Columbia Encyclopedia, Sixth Edition. Columbia Encyclopedia World Factbook Columbia Gazetteer American Heritage Coll. Actinium is a silver-white metal with a cubic crystalline structure. It is found with uranium minerals in pitchblende . The other seven isotopes of actinium have very short half-lives ranging from 10 days to less than 1 min.
Actinium is in group IIIb of the periodic table .
Its chemical properties are similar to those of lanthanum and of members of the actinide series , of which it is usually considered the first member. It was later found to be identical with an element discovered in 1902 by Fritz Giesel and which he called emanium. The Columbia Encyclopedia, Sixth Edition. Click here to shop the Bartleby Bookstore .