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

Tom Mitchell mitch at niftyegg.com
Tue May 27 20:52:36 EDT 2014


Names do change.   It is important to state with precision the source
of the name and the data that matches that source to the material under
study.  And more....

i.e. clarity of what is known and what is pulled from other sources.

There are many cases where the old guard is replaced by new researchers
and the new folk have a new outlook on things.   Some changes reflect
true new insight some are point of view some are gratuitous.

Simple things are of interest.... consider that the inch was redefined
c1959 to be exactly 2.54cm.   This implies that all precision crystal
structure
dimensional measurements prior to this change need an adjustment.
While this is about a 2ppm difference some papers attempt to refine
values to a degree where this comes to play but....

For a land survey this is about 1/8" in a mile....

A quick glance at Dana's Volume III and the five
significant figures seem to  not move quartz.
But what is the sign and the 1/8" for a volume of
rock the size of the Sierra Nevada in the US might
prove interesting.



On Tue, May 27, 2014 at 5:16 PM, Alfredo Petrov <alfredo at mindat.org> wrote:

> The IMA does not "outlaw" ANY mineral names, they merely decide which name
> will be official. You can use the unofficial species or varietal names as
> much as you like without suffering any punishment (except perhaps the
> editing of your mineral names by journal editors).
>
> There is a misconception in some circles that the IMA has "prohibited" the
> use of varietal names or the names of the intermediate plagioclases, for
> example, but this is far from the case. The materials in question have
> merely been demoted from species status to varietal status, and there is
> nothing wrong with using the names when appropriate as long as one
> understands that they are not referring to end-member species. Much like
> astronomers demoted Pluto from its planet status, without any intention to
> ban the name Pluto from the literature [?]
>
>
>
> On 28 May 2014 04:49, Robert Tracy <rtracy at vt.edu> wrote:
>
>> Anachronism it may be in your opinion (and the IMA's) but I will
>> resolutely continue to use the name Sphene whenever I am allowed to get
>> away with it. The IMA has done some stupid things over the years (magnesian
>> ferrosilite anyone?) but the outlawing of the beautiful (and unambiguous)
>> name Sphene is top of my list.
>>
>>  Dr. Robert J. Tracy
>> Prof. of Geosciences
>> Associate Department Head
>> Director, Museum of Geosciences
>> Virginia Tech
>> Blacksburg VA 24061-0420
>> 540-231-5980
>> 540-231-3386 (F)
>>
>>
>>
>>
>> On May 27, 2014, at 11:28 AM, Anton Chakhmouradian 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 G
>> Pa; 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
>>
>> <image003.png>*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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-- 
  T o m    M i t c h e l l
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