[MSA-talk] REE, lanthanides, lanthanoids, Y and Sc

Modreski, Peter pmodreski at usgs.gov
Thu Nov 30 11:55:01 EST 2017


That's all a very interesting story, about Goldschmidt, Hevesy, and Urban.
(I think you meant to write Ct for the discredited symbol for Celtium, not
Ce--maybe even some autocorrect function changed that without your
realizing!)

I appreciated Anton's recap about the REE, Y, and Sc too.

Pete

On Wed, Nov 29, 2017 at 11:41 PM, Gustaf Arrhenius <arrhenius at ucsd.edu>
wrote:

> Classics
>
> An example of application of these principles is the hunt and discovery of
> element 72 where Victor Moritz Goldschmidt searched for it in  titanium
> minerals whereas George Hevesy realized that it ought to be associated with
> zirconium minerals, together with Coster  found it there and baptized it to
> Hafnium after Copenhagen where Hevesy worked with Niels Bohr who  followed
> the progression with deep interest. Meanwhile Urban in  Paris thought that
> the it ought to behave  as a rare earth  element and claimed to have
> identified it  from weak lines in a REE spectrum. The French were
> patriotically unwilling to give up this claim and as of today the symbol in
> French textbooks is always  Ce using Urbains name Celtium for the
> perfidious Hf and disregarding all later confirmatory evidence
>
> Goldschmidt with whom friendships were always extremely fragile was
> momentarily incensed by Hevesy’s omission at a discovery lecture in Berlin
> of not mentioning that one of the minerals found with the highest content
> of hafnium was an alvite from Norway that V.M.G. had provided.  Hevesy’s
> diplomacy however helped to heal the threatening rift and the friendship
> remained for life.
>
> Gustaf Arrhenius
>
>
> > On Nov 27, 2017, at 8:13 AM, Anton Chakhmouradian <Anton.Chakhmouradian@
> umanitoba.ca> wrote:
> >
> > Hello All,
> >
> > Indeed, chemists include Sc and Y in the REE family, whereas geochemists
> do not usually consider Sc as part of that family and are split on the Y
> issue. The difference is: chemists look at elements mostly from the
> standpoint of pure elements/compounds, whereas geochemists look at how
> elements ASSOCIATE with one another in nature. For example, ScPO4 has the
> same zircon-type structure as YPO4, YbPO4 and other heavy-REE
> orthophosphates, so it would seem natural to a chemist to just consider Sc
> as part of the REE family. In reality, Sc3+ is >10% smaller than Lu3+, the
> smallest lanthanide (or lanthanoid, according to the revised IUPAC
> nomenclature). This difference in ionic radii will drive Sc partitioning in
> natural processes, effectively forcing it to either form its own minerals
> or to associate with trivalent or tetravalent cations that are closer to it
> in ionic radius (IR). For example, zircon associated with the scandium
> phosphate pretulite (IR [8]Zr = 0.84 vs. IR [8]Sc = 0.87 A) would contain
> up to 3.2% Sc2O3, whereas xenotime (YPO4) found in the same association (IR
> [8]Y = 1.02 A) <  0.7% Sc2O3 (Moelo et al., Can. Mineral., 40, 1657).
> >
> > The differences in radius do also affect the crystal chemistry and
> metallogeny of Sc. For instance, kolbeckite (ScPO4.2H2O) is isostructural
> with metavariscite (AlPO4.2H2O), not churchite YPO4.2H2O (Yang et al., Acta
> Crystal., C63, i91). In laterites, which are probably the most promising
> future Sc resource (if there is ever any need for much Sc), where this
> element substitutes in Fe3+ oxides and hydroxides (Chassé et al., Geochem.
> Persp. Lett., 3, 105).
> >
> > Yttrium, on the other hand, is a close match for holmium and usually
> present in heavy-REE minerals at CI-normalized levels comparable to those
> of Ho. This is the reason why it is often placed between Dy and Ho in
> chondrite-normalized REE plots. Some minerals (notably, fluorite) exhibit
> departure of Y from this predictable behavior, which is reflected in Y
> anomalies in normalized plots. These anomalies are undoubtedly related to
> differences in Y and Ho speciation in some types of fluids and melts.
> Despite this intimate GEOCHEMICAL association between the lanthanides and
> Y, some geoscientists prefer not to include the latter in the REE family,
> usually without explaining their reasons for doing so.
> >
> > To those interested in learning more about REE, their applications and
> politics behind them, as well as the "rare vs. not-so-rare" debate, I can
> recommend the special issue of Elements Frances and I edited in 2012:
> > http://elementsmagazine.org/get_pdf.php?fn=e8_5.pdf&dr=e8_5
> >
> > Anton R. Chakhmouradian
> > University of Manitoba
> >
> >
> > -----Original Message-----
> > From: msa-talk-bounces at minlists.org [mailto:msa-talk-bounces@
> minlists.org] On Behalf Of Frank Spera
> > Sent: November 26, 2017 5:51 PM
> > To: Don Halterman <donhalterman at comcast.net>
> > Cc: msa-talk at minlists.org
> > Subject: Re: [MSA-talk] REE...
> >
> > well, if i recall the REE include Y and Sc which are NOT rare
> Lanthanides …..but its been a long time since i took an inorganic chemistry
> class!!
> > fs
> >
> > -----Original Message-----
> > From: msa-talk-bounces at minlists.org [mailto:msa-talk-bounces@
> minlists.org] On Behalf Of Don Halterman
> > Sent: November 26, 2017 6:13 PM
> > To: Frank Spera <spera at ucsb.edu>
> > Cc: msa-talk at minlists.org
> > Subject: Re: [MSA-talk] REE...
> >
> >
> > It has been some time since I read the article deprecating the term, but
> I recall the phrase "the elements in question are neither rare nor earths,"
> or words to that effect.  Unlike other matters of terminology, this one
> isn't that critical so I won't pursue the matter further if I seem to be
> the only one who recalls this.
> >
> > Don
> >
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