Didn't know that, what about actinides? I'm under the impression that they're all man-made. If the lanthanides are found in nature, do they serve any purpose or are they just "there"?
Uranium and plutonium are both actinides, just noticed that, so I guess my original assumption is wrong. Thinking about it, americerium is used for smoke alarms, and we use some other weird one for some our radiological equipment in the army, but I'm at a loss for some of the others.
That got me thinking about unstability, so if a lot of these are unstable (are they?), they must be radioactive right? As I understand radioactivty, the element in question will either emit alpha, beta, or gamma radiation or a combination of. Does radioactivty allow for emissions of anything else?