used for element 113. Element 113 was also discovered by a team of Japanese scientists and was named in respectful homage to Ogawa's work. Rhenium is generally considered to have been discovered 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. They also found rhenium in gadolinite and molybdenite. In 1928 they were able to extract 1 g of the element by processing 660 kg of molybdenite. It was estimated in 1968 that 75% of the rhenium metal in the United States was used for research and the development of refractory metal alloys. It took several years from that point before the superalloys became widely used. Characteristics Rhenium is a silvery-white metal with one of the highest melting points of all elements, exceeded by only tungsten and carbon. It also has one of the highest boiling points of all elements, and the highest among stable elements. It is also one of the densest, exceeded only by platinum, iridium and osmium. Rhenium has a hexagonal close-packed crystal structure, with lattice parameters a = 276.1 pm and c = 445.6 pm. Its usual commercial form is a powder, but this element can be consolidated by pressing and sintering in a vacuum or hydrogen atmosphere. This procedure yields a compact solid having a density above 90% of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, or rolled. Rhenium-molybdenum alloys are superconductive at 10 K; tungsten-rhenium alloys are also superconductive around 4–8 K, depending on the alloy. Rhenium metal superconducts at . In bulk form and at room temperature and atmospheric pressure, the element resists alkalis, sulfuric acid, hydrochloric acid, nitric acid, and aqua regia. It will however, react with nitric acid upon heating. Isotopes Rhenium has one stable isotope, rhenium-185, which nevertheless occurs in minority abundance, a situation found only in two other elements (indium and tellurium). Naturally occurring rhenium is only 37.4% 185Re, and 62.6% 187Re, which is unstable but has a very long half-life (≈1010 years). A kilogram of natural rhenium emits 1.07 MBq of radiation due to the presence of this isotope. This lifetime can be greatly affected by the charge state of the rhenium atom. The beta decay of 187Re is used for rhenium–osmium dating of ores. The available energy for