What is the only natural occurring chemical element named after a river?

Rhenium is a natural occurring chemical element; it has symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table.

In 1908, Japanese chemist Masataka Ogawa announced that he had discovered the 43rd element and named it nipponium (Np) after Japan (Nippon in Japanese). In fact, he had found element 75 (rhenium) instead of element 43: both elements are in the same group of the periodic table.

Rhenium is named after the river Rhine (Latin: "Rhenus" meaning: "Rhine"). It received its current name when it was rediscovered by Walter Noddack, Ida Noddack, and Otto Berg in Germany. In 1925 they reported that they had detected the element in platinum ore and in the mineral columbite.

Rhenium has one of the highest melting points of all elements, exceeded by only tungsten. (At standard pressure carbon sublimes rather than melts, though its sublimation point is comparable to the melting points of tungsten and rhenium.) It also has one of the highest boiling points of all elements, and the highest among stable elements.