The early form of the rule derived from Harkins 1917 study of meteorites. He reasoned as others at the time, that meteorites are more representative of the cosmological abundance of the elements. Harkins observed that even atomic number (Z) elements were about 70 times more abundant than those with odd Z. The first seven elements, making up almost 99% of the material in a meteorite, were all even numbered Z. In addition, he observed that 90% of the material consisted of only 15 different isotopes, with atomic weights in multiples of four, the approximate weight of alpha particles. Three years earlier, Oddo made a similar observation for elements in the Earths crust, speculating that elements are condensation products of helium. The nuclear core of Helium is the same as an alpha particle.
This early work connection geochemistry with nuclear physics and cosmology was greatly expanded by the Norwegian group created by Victor Goldschmidt