Sivanium was an element created by Dr. Thaddeus Sivana. This "living metal" (Element no.97) had a curious property: It could easily be fashioned into human shape, duplicating the form and function of every organ, enabling the building of android duplicate Sivanas. When the mad scientist was in ethereal form, from wearing a bracelet of Shazamium, he blackmailed Captain Marvel to create a small army of duplicates of Sivana, made with Sivanium. 
While Sivana was away, Captain Marvel used the metal to create a duplicate of himself, and this in turn enabled the big red superhero to turn the tables on Sivana, using a trap composed of a third new element called Marvelium (Element no.99).
In Captain Marvel Adventures #150, "World of Too Many Sivanas," Sivana discovers a new radioactive mineral, and names it 'Sivanium", but this is not the same "Living Metal" that he had synthesized back in Captain Marvel Adventures #100. This metal is capable of powering Sivana's "Molecular Rearranger" weapon, which transforms people's heads and brains into duplicates of Sivana's own.
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