<http://schema.org/description>
"Astatine, a radioactive chemical element. Astatine, a member of the halogen group of elements, is an extremely shortlived substance; its most stable isotope has a half-life period of only 8.3 hours."^^<http://www.w3.org/2001/XMLSchema#string>
<http://science.howstuffworks.com/astatine-info.htm>