Rhenium
In 1925 in Germany, Walter Noddack, Ida Tacke, and Otto Berg reported that they detected the element in platinum ore and in the mineral columbite. They also found rhenium in gadolinite and molybdenite. In 1928 they were able to extract 1 gram of the element by processing 660 kg of molybdenite.
Read more about this topic: Otto Berg (scientist)