Red mercury
You must have a look at this: Red mercury story at the Reg. A great example of not letting the facts get in the way of a good story. And another example of people being arrested for "being in possession of a foreign sounding name".
Daily Mail readers can now rest safely in their beds, knowing that these people have been prevented from making anything out of something that dosen't exist.
If you're thinking of making something out of a substance that doesn't exist, be careful. As the substance doesn't exist, you can't prove what you were going to make (perhaps a cuddly toy). And as you can't prove what you were going to make (because the raw material doesn't exist) you can't prove that you weren't going to make something dangerous. It can then be presumed that you might have been going to make something dangerous. Coupled with a foreign sounding name, that's enough to get you put away.
Be careful out there!