The Silver Tairona Pendant is the twenty-fifth treasure that can be found in Uncharted: Drake's Fortune.
The Silver Tairona Pendant is found in Chapter 6 - Unlocking the Past. After going upstairs and defeating all the enemies, you'll have to go down a set of broken set of stairs from which you won't be able to climb back up. After this set of stairs is small room with some crates and ammo boxes. The treasure is to the right of the small set of stairs.