Silver Key (The Base)
The Silver Key is a key found in Tomb Raider Chronicles in the level The Base. The key is found twice in the level. For the first time it's found in a metal locker in the same room with the mechanical claw. It's used on a locked door that leads to a stairway going upstairs.
The second time the key is found is when Lara kills a soldier in the room where a fuse is missing from a machine. The soldier drops the key, which is used to another locked door that leads to an upper platform where Lara overhears a discussion between Admiral Yarofev and Sergei Mikhailov.
The Russia section has other Silver Keys in addition to the ones found in The Base. The Submarine has one Silver Key and the Sinking Submarine also has a Silver Key of its own.