<page_title> Primordial nuclide </page_title> <section_title> List of 34 radioactive primordial nuclides and measured half-lives </section_title> <table> <cell> 235U <col_header> Nuclide </col_header> </cell> <cell> 7.04×108 <col_header> Half- life (years) </col_header> </cell> </table>
The primordial isotope, ²³⁵U, has a half-life of 704 million years.