What provisional name was used for rhenium before its discovery?

Rhenium was provisionally called dvi-manganese before its discovery. The name reflected its predicted position relative to manganese in early versions of the periodic system.

Mendeleev and later chemists used Sanskrit-derived prefixes such as eka-, dvi-, and tri- for predicted elements. Eka meant one place below a known element, while dvi and tri indicated two or three places below it. Rhenium was initially associated with the name tri-manganese, but Bohuslav Brauner’s rearrangement of the rare-earth elements led to the provisional name dvi-manganese in 1902.

Rhenium was discovered in 1925 by Walter Noddack, Ida Noddack, and Otto Berg. Its name comes from Rhenus, the Latin name for the Rhine River, rather than from Mendeleev’s provisional terminology. The element is a dense, silvery metal with an exceptionally high melting point and is used in high-temperature alloys and catalysts.

Dvi-manganese is easy to confuse with eka-manganese, which referred to technetium. Eka-manganese was predicted as the element one place below manganese; dvi-manganese referred to the heavier element later identified as rhenium.