Source: cirosantilli/polonium-210

= Polonium-210
{tag=Alpha emitter}
{title2=140d}
{wiki}

The only isotope found on <Earth> because it occurs as part of the <uranium 238 decay chain>, i.e., it is not a <primordial nuclide>.

Interestingly it is a bit less stable than other <isotopes>L such as <Polonium-208> (3 y) and <Polonium-209> (124 y), but those aren't in any Earthly radioactive chain so they don't show up on Earth.