[Rockhounds] REE -

[Rik Dillen]

REE are even used in some very special steel qualities nowadays.
One of the purposes is to use it as a scavenger for sulfur. Manganese is used for that traditionally, but MnS has in
some steel grades the tendency to form large flaky pancake-like structures underneath the steel skin, which, in certain
cases/circumstances might give rise to flake formation. Cerium sulfide on the contrary forms very small, hard spherical
precipitates instead, which improves steel quality. The big drawback is the price, of course (in the steel industry they
don't need grams, but many tons).

Grts,

Rik DILLEN 
Doornstraat 15,  B-9170 Sint-Gillis-Waas 
Belgium 
E-mail rik.dillen at skynet.be 
Homepage : http://users.skynet.be/rik.dillen 
 

-----Original Message-----
From: rockhounds-bounces at lists.drizzle.com [mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Ronald Werner
Sent: Sunday, July 06, 2008 11:36 PM
To: rockhounds at lists.drizzle.com
Subject: [Rockhounds] REE - 

Sorry Kreigh, but some correction is needed here!

REE are to my best knowledge NOT used for doping semiconductors. That's the 
privilige of the group III and V elements.

Tim is of course absolutely right: REE's are not rare at all! They are rather 
abundant, though concentrated in economic quantities in a limited number of 
deposits only. 

China seems to have most of the reserves, but the Mountain Pass deposit in 
California is a major reserve base for the US.

No, we won't run out of REE's in ten years. It will take much, much longer, and 
before that we will have run out of many other elements.

REE's are of strategical importance in numerous high-tech and defence applications. 

Also in our daily life we have become rather dependant on these phantastically 
interesting metals. Especially in optical and magnetical applications they are of 
great importance.

Yes, REE's are boring by appearance, and early scientists had good reasons to call 
them "rare earths". The mixtures of oxides early scientists managed to prepare were 
typically earth-like brownish.

The pure oxides of some are actually quite nice, cerium-oxide being nice yellowish 
and neodymium-oxide light pink. 

I guess modern purists would gladly get rid of such ancient terms like REE's and 
would rather speak of the lanthanides, thereby excluding yttrium, and technically 
seen also lutetium.

I am more a romanticus and will always speak of the REE's and include yttrium and 
lutetium, and will even mention scandium as being rather close to the family.

Good samples of the classic REE's minerals -aeschynite, euxenite, fergusonite, 
polycrase etc.- from norwegian deposits have already become expensive and hard to 
find.

Samples of the REE-containing minerals that constitute present day ore are as far 
as I know basically without any significance for collectors. I believe the Mountain 
Pass ore consists mainly of corns of bastnäsite. Anyone who has ever seen a good 
crystal, please DO correct me!

Regards,

Ronald Werner
Norway





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