1849 $50 Gold Liberty Head "Half Union" (1849)

Intriguing History

The 1849 Half Union was designed as a prototype for a $50 gold coin to handle the enormous volumes of California Gold Rush bullion more efficiently, but Congress never authorized regular production, leaving this unique pattern piece -- reportedly kept by a Mint official as a personal souvenir before eventually reaching the Smithsonian -- as one of the rarest coins in American history.