Thursday, November 18, 2010

Rare Earth Revelry

It has been an odd year for the lanthanides. After decades of sitting, quietly, in a row of their own at the bottom of the periodic table, the rare earth elements have been thrust into the limelight by numerous MSM articles.

As it turns out the REE have been a quiet favorite of geochemists for decades. They are used for everything from determining how stars make chemical elements to keeping the compact fluorescent lights on. And they are the bread and butter of numerous geochemical studies. For example, the latest issue of Geology reports rare earth concentrations in 4 of its 23 articles- and this is a general earth science publication, not a geochemistry specialist journal. Rare Earths are used to in stellar nucleosynthesis, missiles, planetary formation, phosphors, continental evolution, magnets, geochronology, neutron capture, volcanism, lasers, and gas light mantles. There is a lot to know, but I will try to start at the beginning. Their names. If you can't remember the list lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, then I suggest you use a mnemonic.

Next up, stellar nucleosynthesis, and rare earths in stars that died before the sun was born.

Rare Earth Revelry
Week -1
Week 1
Week 2
Week 3
Week 4


Kim said...

Thanks for doing this - when non-geologists fret about not being able to find info about geochemistry, you know there's a need!

If you're taking requests, I've got one. There's a big difference between geochemically interesting concentrations and economically useful concentrations, and I'm not sure the general public (or even undergrads) understands this. (A few years ago, I saw a student paper that said that studying lead isotopes in igneous rocks was important because the igneous rocks were ore deposits. He probably wasn't the only one who didn't pay attention to orders of magnitude in concentrations.)

Michael said...


I have casually read parts of your blog throughout my graduate studies and I am always fascinated by the way you synthesize and report different topics in the geosciences.

I am quite smitten with the rare earth elements myself. I have a few suggestions for your "Rare Earth Revelry" topic:

The orbital chemistry of the rare earths - I always find this interesting in demonstrating the cation charges of the lanthanides + Sc, Y. The orbital filling and geometries also gives rise to some of the non-charge/radius behaviour of the rare earths (e.g., La, Gd...) and becomes important during the fluid-based behaviour of the elements - see for example the lanthanide tetrad effect and the estuarine behaviour of the lanthanides.


C W Magee said...

Dear Michael,
You sound like you know more than I do about recent developments in surficial REE behavior, so if you want to write a guest post, just drop me an email.