The Halley's Comet Meteorite Medallion. 2" diameter (silver dollar-sized) 1 full ounce (28 gm) of Odessa meteorite.

This was produced by a entrepreneur in Tucson, who bit off more than he could chew. The front side was designed by Kim Poor, the back shows the orbits of Halley and the planets. But when it came to actually minting the coins, they found the unearthly, crystalline metal took over 4000 degrees heat to melt, hotter than the surface of the Sun. Fortunately, a new induction furnace was being developed in Arizona which did the trick, but then Oxygen impurities made the medallions brittle. That problem was overcome, but by this time the comet had come and gone. Only a few hundred were made, and only a handful are left.

On the subject of meteorites, because I prefer ancient coins myself, I have been interested in coins depicting meteorites. The well-known ones depict the stone of Emesa, about which I enjoyed the article by A.M. Antoniadi, "On ancient meteorites, and on the origin of the crescent and star emblem", Journal of the Royal Astronomical Society of Canada, vol. XXXIII.5, May-June 1939, pp. 177-184. It can be found online on http://adsabs.harvard.edu/full/1939JRASC..33..177A

Just thought I'd send pictures of a medal with a piece of a meteorite embedded in it. My wife Diane bought this for me from a coin dealer for Christmas 2008. Evidently, this meteorite was discovered by the Spanish in 1576 in Argentina. More info about this particular meteorite can be found at: http://www.meteoritemarket.com/CCinfo.htm