Astatine: The Rarest Element You’ll Never Get to See

If you gathered every bit of astatine on Earth, it would weigh less than an ounce – about the same as two cookies. But you’ll never see it, let alone hold it. Astatine is so radioactive that any solid sample would vaporize instantly from its own heat.
This elusive element, with the symbol At and atomic number 85, is the rarest naturally occurring element in Earth’s crust. It forms as a decay product of heavier elements, existing only in trace amounts before quickly vanishing. Its most stable isotope, astatine-210, has a half-life of just 8.1 hours, meaning it rapidly breaks down into other elements.
Because it’s so scarce, its physical properties remain largely unknown. Scientists believe astatine likely resembles iodine, yet it also shows some metallic behavior. It may be a semiconductor or even a metal, but no one has ever seen a bulk sample to know for sure.
Astatine exists on the edge of two worlds – part halogen, part metal, and completely elusive. One of the rarest and most mysterious elements, it exists just long enough to disappear.