[MSA-talk] Mineral name for perovskite-structured (Mg, Fe) silicate?

Andrea Koziol akoziol1 at udayton.edu
Tue May 27 11:48:53 EDT 2014


(Cautiously raising hand)
I am the one who posted this item on the MSA Facebook page (and in the
group).  This news item came from Science Daily, a usually reputable
resource. I posted it without change.  In the future I'll be more careful.
 I agree, I don't like the use of the term (Mg,Fe)SIO3 perovskite in this
context either.

Note to the wise: think before posting!

Andrea Koziol, MSA Secretary


On Tue, May 27, 2014 at 11:28 AM, Anton Chakhmouradian <
Anton.Chakhmouradian at umanitoba.ca> wrote:

>  For all purposes, MgO with subordinate Fe in the lower mantle IS
> periclase (its rock-salt structure is very robust and persists to > 200 GPa;
> Duffy et al., Phys. Rev. Let., 74, 1371). At ambient conditions, FeO is
> isostructural with periclase and known as the mineral wüstite (in
> addition to metallurgical slags, it occurs in meteorites and a few obscure
> terrestrial environments). The intermediate Mg-dominant members should then
> be termed Fe2+-rich (-bearing) periclase, according to the IMA guidelines.
> The rock-salt structure of FeO transforms into a rhombohedral polymorph at
> 18 GPa, but the presence of Mg seems to stabilize the rock-salt arrangement
> throughout the lower-mantle P range (see, e.g., Lin et al., PNAS, 100,
> 4405). That means that, from the standpoint of nomenclature, we are dealing
> with compressed intermediate members of the periclase-wüstite series. Any
> other name applied in the literature (magnesiowüstite, ferropericlase,
> ferroan periclase, etc.) is not in accord with the IMA recommendations. Of
> course, people still use this “illegal” terminology, just like one can
> still bump into sphene, melanite, picroilmenite and numerous other
> anachronisms in the Min-Pet literature.
>
>
>
> Anton Chakhmouradian
>
> University of Manitoba
>
>
>
>
>
> *From:* msa-talk-bounces at minlists.org [mailto:
> msa-talk-bounces at minlists.org] *On Behalf Of *Charles Carrigan
> *Sent:* Tuesday, May 27, 2014 9:56 AM
> *To:* David Hirsch; MSA-talk (msa-talk at minlists.org)
> *Subject:* Re: [MSA-talk] Mineral name for perovskite-structured (Mg, Fe)
> silicate?
>
>
>
> How about MgO with rock-salt structure referred to as “magnesiowustite”?
> I’ve even seen a reference to FeO as “ferropericlase”.
>
>
>
>
>
> Best,
>
> Charles
>
>
>
> *Charles W. Carrigan, Ph.D.*
>
> *Professor of Geoscience <http://geology.olivet.edu/carrigan.htm> │ Dept.
> of Chemistry & Geosciences <http://geology.olivet.edu/> *
>
> *Director, University Honors Program
> <http://www.olivet.edu/academics/honors-program/> *
>
> Olivet Nazarene University │ One University Avenue │ Bourbonnais, IL 60914
>
> Office: 815.939.5346 │ web<https://plus.google.com/106934864033790932269/about>│
> email <ccarriga at olivet.edu> │ Honors: 815.928.5613 │ Fax: 815.939.5071
>
>
>
>
>
> *From:* msa-talk-bounces at minlists.org [mailto:
> msa-talk-bounces at minlists.org] *On Behalf Of *David Hirsch
> *Sent:* Tuesday, May 27, 2014 9:31 AM
> *To:* MSA public List serve
> *Subject:* [MSA-talk] Mineral name for perovskite-structured (Mg, Fe)
> silicate?
>
>
>
> Friends-
>
> I’ve just read a news release online about the new Zhang, et al. Science
> paper "Disproportionation of (Mg,Fe)SiO3 perovskite in Earth’s deep lower
> mantle”.  Is there a mineral name for the perovskite-structured (Mg,Fe)SiO3
> mineral?  If not, then shouldn’t we come up with one?  It seems to me that
> the name “perovskite” should apply to the CaTiO3 mineral, and that it’s
> wrong to apply it to the isostructural silicate, just as we don’t give the
> same mineral name to halite and galena.  The article title isn’t so bad,
> but when you get news releases that include this kind of thing, then
> there’s a real problem:
>
>
>
> "The prevailing theory has been that the majority of the lower mantle is
> made up of a single ferromagnesian silicate mineral, commonly called
> perovskite (Mg,Fe)SiO3) defined through its chemistry and structure. It was
> thought that perovskite didn't change structure over the enormous range of
> pressures and temperatures spanning the lower mantle”
>
>
>
> The release’s author here has presumably misinterpreted the article’s
> title to infer that “perovskite" is the name of the mantle mineral, rather
> than "(Mg,Fe)SiO3 perovskite”, indicating a perovskite-structured silicate.
>
>
>
> I understand that an official mineral name is not possible, since it
> cannot be found occurring naturally and fully described, but perhaps if the
> community decided on a name we could use in lieu of the (to me) troubling
> "(Mg,Fe)SiO3 perovskite” or worse “perovskite”, then there might be a
> little more clarity and a little less confusion out there, at least among
> mineralogy students.
>
> -Dave
>
>
>
> ============================
>
> Dave Hirsch
>
> Associate Professor
>
> Department of Geology
>
> Western Washington University
>
> alternate email: dhirsch at mac.com
>
> http://www.davehirsch.com
>
> cell: (360) 389-3583
>
> work: (360) 650-2166
>
> fb: http://www.facebook.com/dave.hirsch
>
> ============================
>
>
>
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-- 
************************************************************
Dr. Andrea Koziol
Secretary, Mineralogical Society of America
akoziol1 at udayton.edu
Voice: 937-229-2954
Twitter: @koziolam
http://homepages.udayton.edu/~akoziol1/index.html
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