The raven is a common iconic figure in Norse mythology. The highest god Odin had two ravens named Huginn and Muninn ("thought" and "memory" respectively) who flew around the world bringing back tidings to their master. Therefore, one of Odin's many names was the "ravengod" (Hrafnaguð).
This brooch is based on the Swedish original found in Oland and dating back to 600-700AD. It is made out of Bronze and fastens with a clip and pin at the back