AC 89 ACTINIUM
Actinium starts the series of actinoids (elements 90-103), which are named after this element. It naturally occurs from uranium decay, the half-life of its most stable isotope 227 is less than 22 years. It has very few applications, Chemically, it is similar to lanthanum. Most actinium decays to thorium, about 1.4% to francium.
This is a radiologically pure and representative sample of few micrograms for elements collection.
