[meteorite-list] More ? about Itqiy, Zaklodzie

[Zelimir Gabelica]

Hi Tracy,

Being the lucky owner of slices if similar size (about 2x2 cm) of Itqiy and 
Zaklodzie, I can tell you (qualitatively) that their textures are 
definitely different.
However we all know that a macroscopic texture is very seldom 
characteristic of a meteorite type (most of the ordinary chondrites are the 
best examples).

For "odd" meteorite types, as I am not at all expert, just curious, I love 
to browse through the wonderful web site of David Weir:

http://www.meteoritestudies.com/

David reports (among other features) that, although Itqiy was classified in 
Met. Bull as "EH7-an", "while similarities do exist between Itqiy and EH or 
EL chondrites, the many inconsistencies make a definitive assignment (to EH 
group) tenious..."

Founded upon the recent report published by "Keil & Bischoff, 2008" (so 
cited), he also states that:

"Itqiy is very similar to NWA 2656 (btw classified as "E-achon" in Met. 
Bull.) "with which it shares many textural and morphological 
characteristics"...and also:
"that both may have formed on the same parent body, distinct from that 
associated with EH, EL, Shallowater and aubrites"...

We all know that one should only rely on the officially published data in 
Met. Bull. database.
However as, on one hand, Weir very often reports data from recent 
publications (that he obviously summarizes or to which he possibly 
sometimes just adds some (to me always pertinent) comemnts) and, on the 
other hand, such data are not (always) reported in the database that, as 
one can understand, are not easy to update continuously, I like to keep 
Weir's updatings in mind for my best understanding, hoping that the new 
publications will sooner or later be taken into account officially.

This being, I don't have the paper of Keil and Bischoff on hand to better 
compare.
Perhaps Bernd can help ?

Regarding similarities between Zaklodzie (classified in Met. Bull. as "E 
achon-ung" but that recent studies by Keil (2007) and Keil & Bischoff 
(2008) rather classify as E imb chondrite) and Itqiy, I encourage you to 
read the very informative statements Weir reports regarding Zaklodzie.

He concludes:

"...despite the very close similarities between Zaklodzie and the ungrouped 
enstatite achondrite Itqiy, their chemical end mineral compositions, noble 
gas contents and terrestrial ages EXCLUDE an origin of both meteorites from 
a common parent body".

I am just reporting here some published data and my poor expertise in that 
domain does not pretend to solve the question. As a scientist, I learned 
that we should be cautious with new data but that, on the other hand, there 
can also be always some (minor or major) thruth behind.
Assembling and summarizing (with expertise) such data is, among many other 
merits, the deep interest of David Weir's statements.

I hope this helps.

My best,

Zelimir


A 01:25 13/12/2008 +0000, tracy latimer a écrit :

>I have now heard from at least 3 parties who say that Itqiy is closest in 
>composition to Zaklodzie (and a couple of people who gently corrected my 
>typewriter dyslexia, Saint-Sauveur rather than Saint-Severin!).  The 
>pictures I have been able to find of Zaklodzie, however, don't show the 
>texture very well; to my uneducated eye, it looks more like a common H5 
>(heresy!).  One of the things I find striking about Itqiy is the coarse 
>grained crystals that look almost like commercially available black 
>granite slab.  Anyone who has access to both Itqiy and Zaklodzie slices, 
>do they actually look similar in section?
>
>I have to do more research into the processes that produce 2 so dissimilar 
>textures with almost the same chemical makeups...
>
>Tracy Latimer
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Prof. Zelimir Gabelica
Université de Haute Alsace
ENSCMu, Lab. GSEC,
3, Rue A. Werner,
F-68093 Mulhouse Cedex, France
Tel: +33 (0)3 89 33 68 94
Fax: +33 (0)3 89 33 68 15