I see Helios has that one (and only that one)--but now I'm more confused...
I went back to check that it *was* Promethium that should be unavailable, and Scholten indeed says: "Promethium is not found on earth, due to its radioactive decay. ... [It] is still recovered from the by-proudcts of uranium fission ...."
BUT in the next sub-section, 7.1 Promethium metallicum, he continues: "Promethium originally didn't exist on earth because it's too radioactive. ... Promethium is used in batteries..."
By contrast, there's plenty of reference to it on the web! E.g., from
http://www.webelements.com/promethium/: "promethium metal is available commercially so it is not normally necessary to make it in the laboratory.... Pure promethium is available through the reduction of PmF3 with calcium metal."
Wikipedia talks about properties and half-lives of it in metal form, and also of various of its salts. Both sites note that it is not found *in the Earth's crust*, which may be where the idea comes from that it is "not found naturally on the earth"?? Both note that its longest-lived isotope is 17+ years.
So I was quite mistaken in calling it "imaginary", and remedy certainly *could* be made from it, tho I assume it would be expensive to obtain, and triturating a highly radioactive substance... well, there's some challenge there...
Just for fun, here are some more interesting notes from
http://www.lenntech.com/periodic-chart- ... /pm-en.htm: "Promethium is a rare-earth metal that emits beta radius. It is very radoiactive and rare, so it is little studied: its chemical and physical properties are not well defined. Promethium salts have a pink or red colour that coluors the surroundings air with a pale blue-green light.
Applications
Most promethium is used for research purpose. It can be used as beta radiation source in luminous paint, in nuclear batteries for guided missiles, watches, pacemakers and rados, and as a light source for signals. It is possible that in future it will be used as portable X-ray source.
Promethium in the environment
Promethium dose occurs in the Earth's crust in tiny amounts in some uranium ores. It is not stable so it undergoes radioactive decay. All the promethium which might once have existed on Earth when it formed would have vanished within 10000 years.
Health effects of promethium
Promethium has no role to play on living things and is slightly dangerous because of its intense radioactivity. Test on animals showed that it become localized on the surface of bones from which it can be only slowly removed.
Environmental effects of promethium
Promethium is practically non-existent in nature, so it poses no threat to the environment. It has to be haldled carefully because of its high radioactivity."
So we should at some point be able to get triturated Promethium remedies, and it sounds like a picture that would find use...
Shannon