Inspired by the same article, Dave Hamric of Metallium, Inc. (eBay userid hamric) has embarked on an ambitious project to create coins from every possible mintable metal element. Their inventory is constantly growing and can be found on eBay or ordered directly at www.ElementSales.com.
Theodore Gray's fascinating Wooden Periodic Table is full of information about the elements and beautiful pictures of them in their pure form.
Dark gray boxes represent elements that, for one reason or another, can not be made into a coin. It could be because they are too radioactive, or poisonous, or caustic, or react violently with air or water. Or it could be simply that they are a liquid or a gas at room temperature.
Fred Zinkann (eBay userid equillink) makes beautiful trial issues or "fantasy pieces" in various exotic metals. These are not legal tender, but they do have a denomination and bear the name of real places.
The Shire Post (ebay userid tmaring) has coins in exotic metals from worlds all over the Multiverse. Their coins can be found on eBay or ordered directly from Tom Maringer at www.ShirePost.com.
The images are all taken using a Vivitar 4000 PoS (er, point and shoot) on Macro setting at about 4 inches. No flash is used, but a GE soft white twisty fluorescent bulb provides lighting. I attempted to adjust white balance, but I don't have a white reference card, so the pics are all off a bit into the yellow.
I've tried to scale all the pictures the same, so all the coins should be approximately proportional in size.
The rest of this page is sort of a place holder for elements I don't yet have.
Hydrogen
Hydrogen is an explosively flammable gas, which could not be made into a coin. At extreme pressure
(such as the core of the planet Jupiter), hydrogen becomes a metal. However it is not known whether
metallic hydrogen would retain its state when the pressure is reduced to normal. And as an alkali metal,
metallic hydrogen might react too quickly with air and/or water to be stable for use as a coin. It would
be light though!
Helium
Neon
Argon
Krypton
Xenon
Radon
These are noble gases, which can not be made into a coin, or even made into a compound which
could be formed into a coin shape. In addition, Radon is radioactive.
Uranium
Uranium scares people, who tend to associate it with atomic bombs and '50s Japanese monster movies.
Chemically, uranium is only slightly toxic. Radioactively, uranium emits mostly alpha particles
which cannot penetrate skin or paper. So, as long as it stays outside the human body, uranium
is harmless. Ingesting or inhaling uranium or its compounds, however, would not be a good idea.
Also, uranium is pyrophoric, which means that fine particles or powder can spontaneously catch fire,
which would produce radioactive uranium oxide smoke, which would not be good to breathe because
it's not water soluble and so would sit in the lungs forever, emitting its alpha particles directly into the
lung cells, and eventually after many years you'd get lung cancer.
Natural uranium consists of 99.28% U-238, 0.71% U-235, and 0.0054% U-234. Bombs and reactors require U-235, so isotope separation is used to produce Enriched Uranium, which has a much higher percentage of U-235. What's left over is called Depleted Uranium (DU), which contains only 0.2 percent U-235. All the uranium isotopes are radioactive, but U-238 is much less radioactive (and therefore less dangerous) than U-235.
Depleted uranium is fascinating stuff. It's very dense, thus it is used in applications where denseness is a virtue, such as aircraft trim weights, sailboat keel counterbalances, oil drills, and gyroscope rotors.
Uranium's density, hardness, and pyrophoricity combine to make it uniquely perfect for a special application: armor-piercing projectiles. When a pointed spike of DU is fired into an armored vehicle such as a tank, it first begins to penetrate the armor. As it penetrates, it spalls, which means that it fractures away from the sides of the point, thus causing the spike to be self-sharpening. Then, the heat of impact and penetration cause the uranium to partially liquefy. Once through the barrier, the suddenly uncompressed molten uranium expands into a fine mist, which spontaneously ignites explosively, spewing flaming molten radioactive metal and smoke on the occupants. Very effective and elegant.
DU has ironic uses. One such use is protective plating against armor-piercing rounds! The M1 Abrams tanks have been fitted with DU plates sandwiched between steel. Another ironic use is as shielding containers for highly radioactive medical and industrial sources. Apparently, although DU is slightly radioactive, it is much less radioactive than the object stored inside it.
A coin of DU is possible, though not desirable for a circulating piece. First, manufacture would be quite difficult. Machining DU (rolling, cutting and blanking) would likely generate small uranium shards, which could spontaneously burn in the air, creating radioactive smoke. Machining would have to be done under an inert gas such as nitrogen or argon, and the debris disposed of properly.
Then, even if you could find pre-made blank planchets, there's another problem: uranium is extremely hard, so it would be difficult to strike with decent relief. It would probably wear out the dies quickly. Finally, uranium oxidizes fairly quickly in air, turning to an unappealing dull black color. This oxide rubs off when handled, so you'd end up with radioactive dust on your fingers and around the house. The only option would be to seal it in an airtight container or give it a heavy coat of laquer.
There are only two companies in the US that make depleted uranium products for the civilian sector. Neither one will deal with an individual who does not have a radioactive materials handling license. Nevertheless, I have hope that some day someone will make me a depleted uranium coin.