Actinium was first isolated in 1899 by French chemist André-Louis Debierne, a French scientist. Actinium is a soft radioactive metal that reacts with oxygen to form a layer of actinium oxide. It is not found naturally in the earths crust but exists in ores of uranium and thorium. It emits beta and alpha particles. It does not have many uses due to its rarity but it is used in nuclear generators of spacecraft with other elements as a neutron source. It has been researched for its use in radiotherapy due to its short half life and beta production. It is a solid metal at room temperature and it has a melting point of 1227°c and a boiling point of 3200°c.