56 Barium (Ba)
atomic weight 137.3, melting point 729° C, density 3.62g/cc
Barium medal by Metallium, Inc. Photo used by permission.
Diameter 19 mm, 1.5 grams, 99.9% pure. $62 on 7/16/2009.
According to Metallium, "the process to make the coins and seal them in glass is complex and time consuming." If it were not sealed in a glass capsule it would corrode rapidly in air.