[Rockhounds] REE -

[Axel Emmermann]

Indeed my friend!
Cerium is also a good replacement for Mn2+ in fluorescent calcite... The
so-called Terlingua Type Calcite.
Beautiful pink fluorescence under LW-UV.

Greetzzzz 
Axel

> -----Oorspronkelijk bericht-----
> Van: rockhounds-bounces at lists.drizzle.com 
> [mailto:rockhounds-bounces at lists.drizzle.com] Namens Rik Dillen
> Verzonden: maandag 7 juli 2008 19:35
> Aan: 'Rockhounds at drizzle.com: A mailing list for rock and gem 
> collectors'
> Onderwerp: RE: [Rockhounds] REE - 
> 
> 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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