This sample of uraninite contains some about 10-6 grammes of actinium at any one time. Image adapted with permission from Prof James Marshall"s (U. North Texas, USA) Walking Tour of the elements CD.
Protactinium has a bright metallic lustre which it retains for some time in air. The element is superconductive below 1.4 K. The element is a dangerous toxic material and requires precautions similar to those used when handling plutonium. Protactinium is one of the rarest and most expensive naturally occurring elements. The element is an a-emitter and is a radiological hazard similar to polonium. Protactinium is a highly toxic and radioactive rare earth metal that requires special handling. It is found in pitchblende and ores form Zaire and is one of the rarest and most expensive naturally occurring elements.
Here is a brief summary of the isolation of protactinium.