Roentgenium

Roentgenium is element 111. Just weeks after making darmstadtium, the same team at the GSI laboratory in Darmstadt, Germany, made it in December 1994 by fusing nickel nuclei with bismuth. They detected three atoms. It was named in 2004 after Wilhelm Röntgen, who discovered X-rays in 1895.

Roentgenium sits below copper, silver and gold, so it might be expected to act like a heavy precious metal, though relativity's effect on its electrons could make it quite different. Nobody has tested that: only a few atoms have ever been made, and they last from fractions of a second to a minute or two.