This brooch is based on a finding from Borre in Denmark, dating back to around the year 1000. It’s a very beautiful brooch in the Urnes style, a Viking Age art style that emerged in the Nordic regions during the later part of the 10th century, named after the Urnes Stave Church in Sogn, Norway.
See: Borre finding
Made of bronze.
These brooches from Denmark are also very similar: