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 is the only coin in the series with a ribbed edge, which comes about because, unlike the others that are stamped from blanks punched out of sheets, this one is stamped over the top of some other gold coin (in the rotation video you can actually make out faint traces of the date from the old coin, invisible to the naked eye). I guess it was just cheaper and easier this way: No wasted gold.
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: 14 January, 2007
Sample Group: Coins