Dianium was the proposed name for a new element found by the mineralogist and poet Wolfgang Franz von Kobell in 1860. The name derived from the Roman goddess Diana. During the analysis of the mineral tantalite and niobite, he concluded that it does contain an element similar to

niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

and

tantalum Tantalum is a chemical element; it has Symbol (chemistry), symbol Ta and atomic number 73. It is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductility, ductile, lustre (mineralogy), lustrous, blue-gray transition ...

. The symbol was Di. Following the rediscovery of niobium in 1846 by the German chemist Heinrich Rose,

Friedrich Wöhler Friedrich Wöhler Royal Society of London, FRS(For) HonFRSE (; 31 July 180023 September 1882) was a German chemist known for his work in both organic chemistry, organic and inorganic chemistry, being the first to isolate the chemical elements be ...

, Heinrich Rose, R. Hermann and Kobell analysed the minerals tantalite and

columbite Columbite, also called niobite, niobite-tantalite and columbate, with a general chemical formula of , is a black mineral group that is an ore of niobium. It has a submetallic luster, a high density, and is a niobate of iron and manganese. Niobite ...

to better understand the chemistry of niobium and tantalum. The similar reactivity of niobium and tantalum hindered preparation of pure samples and therefore several new elements were proposed, which were later found to be mixtures of niobium and tantalum. Rose discovered pelopium in 1846, while Hermann announced the discovery of ilmenium in 1847. In 1860, Kobell published the results on the tantalite from a quarry near

Kimito Kimito (; ) is a former municipality of Finland. On January 1, 2009, it was consolidated with Dragsfjärd and Västanfjärd to form the new municipality of Kimitoön. Prior to the consolidation, it was one of the four municipalities located ...

a village in

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

and columbite from Bodenmais a village in Germany. He concluded that the element he found was different from tantalum, niobium, pelopium and ilmenium. The differences between tantalum and niobium and the fact that no other similar element was present were unequivocally demonstrated in 1864 by

Christian Wilhelm Blomstrand Christian Wilhelm Blomstrand (20 October 1826 – 5 November 1897) was a Swedish mineralogist and chemist. He was a professor at the University of Lund from 1862-1895, where he isolated the element niobium in 1864. He developed an early version o ...

, and Henri Etienne Sainte-Claire Deville, as well as by Louis J. Troost, who determined the formulas of some of the compounds in 1865 and finally by the Swiss chemist

Jean Charles Galissard de Marignac Jean Charles Galissard de Marignac (24 April 1817 – 15 April 1894) was a Swiss chemist whose work with atomic weights suggested the possibility of isotopes and the packing fraction of nuclei. His study of the rare earth elements led to ...

. Both tantalum and niobium react with

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

and traces of oxygen, including atmospheric concentrations, with niobium forming two compounds: the white volatile

niobium pentachloride Niobium(V) chloride, also known as niobium pentachloride, is a yellow crystalline solid. It hydrolyzes in air, and samples are often contaminated with small amounts of NbOCl3. It is often used as a precursor to other compounds of niobium. NbCl ...

(NbCl₅) and the non-volatile niobium oxychloride (NbOCl₃). The claimed new elements ''pelopium'', '' ilmenium'' and ''dianium'' were in fact identical to niobium or mixtures of niobium and tantalum.

References

Misidentified chemical elements {{chem-hist-stub