The element after gold in the series: copper, silver, gold, ... It is element 111, a heavy radioactive element that can be produced artificially, in tiny quantities.
Back in 1980 I became interested in this element because the nested sequence of genies and lamps described in the narrative on page 112 of Godel, Escher, Bach by Douglas Hofstadter ended just before naming it. It seemed to be lacking something for having to stop so soon.
In 1994 scientists managed to synthesize a few atoms of element 111. The experiment was repeated in 2000, then independently confirmed in 2003; a total of 20 atoms were produced in the three experiments. The element was named Roentgenium in 2004.
This page was written in the "embarrassingly readable" markup language RHTF, and was last updated on 2018 Aug 27. s.11