text: The 4n+2 chain of uranium-238 is called the "uranium series" or "radium series". Beginning with naturally occurring uranium-238, this series includes the following elements:  astatine, bismuth, lead, mercury, polonium, protactinium, radium, radon, thallium, and thorium.  All are present, at least transiently, in any natural uranium-containing sample, whether metal, compound, or mineral. The series terminates with lead-206.
  The total energy released from uranium-238 to lead-206, including the energy lost to neutrinos, is 51.7 MeV.