No one has ever seen astatine, which shares the distinction of being one of the rarest naturally-occurring elements on earth. Find out more with Allan Blackman from AUT in episode 8 of Elemental.

Astatine is an enigmatic chemical element whose name means unstable.

Along with francium, astatine has the distinction of being the rarest naturally-occurring element on earth. Ironically, element 85 was actually synthesised in the laboratory before it was finally found in nature.

Professor Allan Blackman from Auckland University of Technology tells us everything we know about astatine - which is not much.

The Elemental podcast is celebrating 150 years since the periodic table was first published by Russian chemist Dmitri Mendeleev.

We are exploring the periodic table alphabetically, and astatine is the last of the As. So far we have looked at actinium, aluminium, americium, antimony, argon and arsenic.

Go to this episode on rnz.co.nz for more details