Which element other than transuranic elements was first created in lab and then found in Nature in trace amounts as by-product of natural radioactivity?

Technetium (Tc, atomic 43) was first artificially synthesized in 1937 before being found in nature, making it the first non-transuranic element with this distinction. It was later discovered in trace amounts in uranium ores as a spontaneous fission product. Fermium is transuranic, while actinium and columbium (old name for niobium) occur naturally.