Actinium is the fourth rarest naturally occurring element after astatine, francium and polonium. It is found in infinitesimally small quantities in uranium ore. Its most impressive quality might be the intensity of its decay. Ac-227 has a half life of only 21 years making it some 215 million times more radioactive than depleted uranium. Pool together enough of this material to make it visible, say a milligram or two, and you’d witness the eerie blue glow of Cherenkov radiation. You might also regret the folly of your decision to get so close to admire that little glow because in a few years your body will probably be ravaged with cancer. A thousandth that amount is for sale here - a prudent yet still compelling amount of this exotic and dangerous concoction.

The challenge for the amateur enthusiast undertaking this project is not so much in the acquisition of the starting sample. High grade uraninite is easily available on eBay. Concentrating and isolating the fleetingly small amount of actinium from the vast mass of other elements in that chunk of rock - especially the other trace radioactive elements - is far more difficult.

The solid amount of material in this ampule is lead sulfate which is the carrier upon which the small amount of actinium sulfide is deposited. In all, an estimated 0.1 nanogram (some 10 nanocuries) of this metal is scattered about on these dust particles. The screenshot of the spectrometer and software analysis confirms both the presence of the Ac-227 isotope as well as the absence of other radioactive contaminants like thorium and uranium. Note that the energy peak of Th-227 and Ra-223 shown are not contaminants but rather are being created by the breakdown of the actinium itself. These belong to its decay chain which, eventually, ends in a new element; the stable but quite dull isotope of lead Pb-207.

Unlike most of our other acrylic cubes, this microscopic sample of actinium comes with a relatively short expiration date. Prepared in 2020 the last of its atoms will be torn apart within another century or so. If any of us are still around, we’ll be happy to take the cube back in the year 2100 and give you a fully reinvigorated new sample free of charge ;-)