Cupro(Latin for copper) and Pupa
Argentum, follows the Cu -> Ag -> Au pattern, and chrysalis.
I feel I'm happy with what I've got so far, although I welcome any feedback or suggestions for improving these names. Out of the ones suggested already, I'm not really a fan of any :/
Whilst the IRC joint community submission has probably got the most popularity, I'm bothered by how it uses the latin name for copper, followed by the english name for silver, followed by the latin name for gold, in the transitions.