Chemists/physicists/geologists: what's up with Ytterby, Sweden?

Just found about this very happening town, for a while. I read [no cite] some wag called it “the Galápagos Islands of the periodic table.”

yttrium (Y), erbium (Er), terbium (Tb), ytterbium (Yb)
holmium (Ho), thulium ™, and gadolinium (Gd)

How much of the town/mine/events are due to those elements being clustered there and only (mainly) there on Earth? A result of similar research or researchers because of a burst of scientific interest following certain clues which by convenience were easily traced to earth samples already analyzed? A combination, but heavier on one side?

No doubt it would help if I knew what a rare earth and a lanthanide was, but I haven’t a clue.

How about Lawrencium, Livermorium, Berkelium, Californium, Americium? Pretty well the address of the labs in elemental form.

Well, yes. That would be from my second supposition.

  • heh. Sounded like suppository … *

This helps a bit:

“These are the only ones of which the news has come to Harvard…”

I just want to note that the main source of rare earth elements(REE) today is China, not Sweden. But several years ago, the Chinese got worried about having an adequate supply for their own manufacturing, so they restricted their export. That caused the prices to rise, which lead to mines in other countries being reopened (the Chinese had been underselling everyone else). Also various research programs were undertaken to reduce the use of REE in various products.

Despite their name, REE aren’t all that rare, although high quality ores are.

It’s not that those elements are clustered only in Ytterby, it’s just that Ytterby was the REE deposit that was most accessible to early 19th century European scientists. It also probably helped that it was a pegmatite ore, which forms very large crystals that would have given early mineralogists a clue that something was going on with them simply looking at a hand sample.

Seems that there was something a while ago about rare earth elements (Lanthanide series) sometimes being not so rare.

Along the lines of X is supposed to be a rare earth element, but it’s not nearly so rare as Y, which is not. And then there’s…

It is not that Ytterby is particularly unique, it is just that there elements (probably because they have similar physical properties) tend to occur together, in mixed ores, and Ytterby just happened to be the first place where such ores were discovered, and came to the attention of chemists, at a time when chemical knowledge and techniques had reached a stage at which it was able to identify elements. Places where such ores are to be found are fairly rare, but there are lots of them throughout the world.

There is a further question about why such elements tend to occur together, and indeed, why certain elements get concentrated into ores at all, instead of being distributed more or less even throughout the body of the Earth (which would make them much more difficult to discover, let alone extract in useful quantities). I may have this wrong, but I think ore formation generally has to do with how stuff of different melting points and perhaps densities fractionates out within molten rock. That is why I said that it is probably similar physical properties that causes these elements to tend to occur together. (Do we have a geologist on the board who actually knows about this stuff? _ is it Mr Dibble who is a geologist? Someone is I think.)

I’m not a geologist, but I think there’s a chemical component to it as well. Otherwise I can’t see why silver and gold would tend to be found in the company of copper: They have different melting points and densities, but are all in the same column of the periodic table.

Were they that short of names that four different elements are named after Ytterby?

It has occurred to me over the years that perhaps meteors rich in certain elements randomly land in certain areas and that explains the concentrations.

Just now it seems that that may be only partially explain it.

REEs do have very similar chemistries. They’re a pain to separate on purpose, and underground hydrothermal and redox processes don’t do it any better.

The process you’re looking for is fractional crystallization.

The important thing isn’t the melting temperature of the elements themselves, it’s the melting temperature of the minerals. Or, more precisely, the temperature and pressure conditions at which the minerals will crystallize out of a liquid magma. As a magma chamber cools and minerals form and drop out, it removes the elements that make up those minerals from the remaining liquid melt, which in turn affects what kind of minerals can form later in the cooling process. This is why we have different kinds of intrusive igneous rocks, but importantly to the subject at hand as the fractional crystallization process continues and more and more minerals drop out, the incompatible elements (the ones that don’t easily fit into minerals) become more and more concentrated in the remaining liquid magma.

So if you imagine two magma chambers of identical original composition, if one cools very quickly you’ll get a homogenous rock that’s similar to the original composition, with the incompatible REE’s spread out throughout the cooled rock in economically unrecoverable concentrations. If the other one cools slowly and undergoes lots of partial melting, however, the REEs will be concentrated in the last bits of magma to cool and will either form oddball exotic minerals or simply solidify in their native elemental state. Either way, it concentrates them in a much smaller area.

(Definitely a massive oversimplification, but that’s sort of the gist)

It doesn’t explain it at all.

The only places I know of where meteor impacts caused ore concentrations are the Sudbury Basin and Vredefort crater. Those were very large impacts, but the ores come from material already on the Earth. The impacts just stirred things up. And for big impacts, the meteor is usually vaporized during the impact.

It has always struck me as rather a lack of imagination on the part of their discoverers.

Kinda yes. This is only true for primary ores, for others it’s mostly about the solubilities of the components in hydrothermal fluids, not molten rock.

I was, but haven’t been a practising one for years. I still consider myself one by training, though.