Dave Hamric sells element samples under the name Metallium. He's developed a line of coins struck out of various common and uncommon metals: They are quite lovely, and very reasonably priced, considering the difficulty of creating some of them.
This coin has a unique complication: It melts at slightly above room temperature (29.8C, 85.6F). It arrives sandwiched between a pair of ice packs in an insulated box, along with a warning to keep it cool at all times (I'm keeping it in an unheated basement rather then with the rest of my collection, which is in an office building that would quickly reach the melting point of gallium were the power to fail for any length of time in the summer.) Needless to say, gallium is not likely to catch on as a metal for coinage, except maybe on Pluto.
Here is the back side of this coin (click either picture to see it larger):
Click the Sample Group link below to see many other coins made of various elements, or click the link to his website above if you want to buy one like this.
Source: Dave Hamric
Contributor: Theodore Gray
Acquired: 1 December, 2006
Text Updated: 29 January, 2009
Sample Group: Coins