摘要
Searching for transuranium elements in nature is an important work, and its significance has been widely emphasized by many scientists. The research regarding distribution and genesis of <sup>239</sup>Pu may find a way of searching for heavier transuranium elements in nature. Moreover, it can provide important evidence for naturally occurring nuclear reaction and neutron source. Many scientists carried out determination of plutonium in uranium ores, but many of the early determinations gave only estimation of <sup>239</sup>Pu content in the ores because no isotope spike was used to determine the chemical yield of the plutonium separated from the ores.
