Isotopes of barium Isotopes of barium Naturally occurring barium (Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, recently identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks). This nuclide decays by double-electron capture (absorbing two electrons and emitting two neutrinos); with a half-life of (0.5–2.7)×10 years (about 10 times the age of the universe). There are a total of thirty-three known radioisotopes in addition to Ba, but most of these are highly radioactive with half-lives in the several millisecond to several minute range. The only notable
Sterling silver Netherlands, the Baltic, Germany, and even deeper regions of central Europe." The sterling alloy originated in continental Europe and was being used for commerce as early as the 12th century in the area that is now northern Germany. In England the composition of sterling silver was subject to official assay at some date before 1158, during the reign of Henry II, but its purity was probably regulated from centuries earlier, in Saxon times. A piece of sterling silver dating from Henry II's reign was used as a standard in the Trial of the Pyx until it was deposited at the