Rare earths

I did a search on rare earths, suspecting this had been answered before, but came up blank. What classifies an element as a rare earth. Also, I get the reason for the first part of the name, but why earths?

Rare earth elements, but it doesn’t explain why they’re called that.

On the other hand, Here is the explanation of how the rock and roll band Rare Earth picked their name.

Rare earths are the oxides of the rare earth elements (that is, the actinide and lanthanide elements). They’re called that because they (1) scarce (rare) and (2) they are oxides, and hence not metallic (earth). The elements themselves are metals, though.

I suppose originally, any element derived from a rare soil type might have been considered a rare earth element, but these days they’re defined by atomic number.

Nametag, let me make sure I have this right.

Rare Earth Elements are the elements listed in the link I provided above. Uranium for example.

But Rare Earths are the oxides of those elements?

Actually, I’ve read that most of the rare earth elements really aren’t all that rare, but they were formerly difficult to extract from their ores, and each other, as they frequently occurred together.
Cerium is supposedly more common than lead, and I don’t think uranium itself is all that rare. Though of course, U-235 is much, much rarer than U-235.

Yah. Possibly any mineral containing such elements, but it’s usually understood to mean the oxides. Pitchblende, which is mainly UO[sub]2[/sub], is a rare earth (although it generally contains radium too).

I swear, I’ll never understand chemistry.

I used to Christmas shop at Rare Earth in Ashland, OR. I love that store.

Rare earth elements were originally thought to be rare. They are not, they are just hard to extract and separate from each other. This has to do with their outermost electrons all lie in the f-shell.


You meant U-235 is rarer than U238, no?