For them a primordially luminous mind cannot be contaminated by adventitious defilements. It may also mean "having a self-contained origin", being primordially Existent, without an origin, self-existent. This nuclide occurs primordially, and has never been observed to decay to the ground state. Radon is entirely radiogenic, since it has too short a half-life to occur primordially. Uranium has the highest atomic weight of the primordially occurring elements. This ground is said to be primordially pure (ka dag) and spontaneously present (Ihun grub).