This pendant depicts Mjolnir, the magical hammer of the god Thor. Such pendants worn as good luck charms during the viking age.  They were common throughout all the scandanavian countries. This Thor's hammer pendant is a full-sized copy of the original, which was found in Skåne, Sweden, and currently resides in the Swedish National Museum.  
It is just shy of 2" tall (49mm) and weighs 2.1 ozt/69g in silver, 60 grams in bronze.  This pendant is available in my Etsy Store