This shiny gold bar is one of the many treasure items you may find along the way
Treasure Items are various riches found throughout the game Return to Castle Wolfenstein. They consist mostly of gold bars or chalices, but occasionally, B.J. Blazkowicz may come across things like crystal skulls or gemmed helmets. Once obtained, a special sound will play and the game notifies you that you found one of them.
In RtCW: Operation: Resurrection,the Treasures in Northern Egypt include a gold head statue of a Pharaoh & a Golden Cat.
Treasure items are mostly found in secret areas, its only use in game is to perfect the level score, unlike the treasures in Wolfenstein, which are used as currency to upgrade your weapons or purchase ammunition.