Albertus Magnus is often credited with isolating this element around 1250; it's since been used as a poison
[DOC] [TLE] h2g2 - The Elements: Names and Origins - A-E - Edited Entry [PAR] Mar 10, 2005 ... Actinium is a radioactive element, named after its radioactive property to ... which 
in its turn had already been used by the ancient Greeks and Romans, ... time from 
this mineral in 1250 by Albert von Bollstadt (aka Albertus Magnus).