That is korean. It seems to be some sort of marriage/wedding token. As for the composition of the metal. I couldn't tell you. Interesting piece though. I would like to have it in my collection purely since it is Korean EDIT - Oh snap - I found it: http://www.imperialjapanmedalsandbadges.com/koreancrownprince.html
A bit more info: Crown Prince’s Wedding Medal: instituted by Emperor Kwangmu to commemorate the wedding of his eldest son and heir apparent, the future Emperor Yung-hui, on 24th January 1907. Awarded as a circuler medal in three classes (1. First Class in solid gold – limited to the Imperial Family, 2. Second Class in solid silver – conferred on nobles and those of officer rank, and 3. Third Class in bronze – commoners, junior officials and other ranks). Ribbon: 36mm moiré divided into stripes of red 6mm, deep blue 5.5mm, and yellow 12.5mm.