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Magnesiohornblende, Eifel Germany

Posted by Olav Revheim  
Magnesiohornblende, Eifel Germany
November 30, 2010 06:07PM
    
According to the information on the locality page Nickenicher Sattel (Eicher Sattel), the photos:

© 2008, JGW
© Chinellato Matteo
.
© Chinellato Matteo

in the magnesiohornblende should probably be moved to the amphibole group gallery.

Same probably goes with:

© Dan & Diana Weinrich Minerals


also labeled magnesiohornblende, but from Monte Somma/Vesuvius in Italy

Olav



Edited 3 time(s). Last edit at 11/30/2010 08:11PM by Rock Currier.
avatar Re: Magnesiohornblende, Eifel Germany
November 30, 2010 08:22PM
    
“magnesiohornblende should probably be moved to the amphibole group gallery”
We can do that. For me it is/was more interesting to show, how the “misidentified magnesiohornblende looks like.
Christof
avatar Re: Magnesiohornblende, Eifel Germany
November 30, 2010 09:38PM
Christof - I have no opinion one way or the other, lets get it right! Unfortunately, almost all of the references listed for the locality are all in German?, which I can't read or access, so I can't check to see if there are any published analysis which could provide a clue. Since you are the only editor of this mineral entry, what was your basis for the "erroneously and without analytical data named Magnesiohornblende" statement - have you analyzed any of these. I photographed the specimen from a reliable source who takes great care in accurate identifications, although mistakes and errors do arise.

Also, there are some identical appearing images of orange prismatic crystals under 'kaersutite' - [www.mindat.org] - one of these has been confirmed , could these "magnesiohornblendes" all be kaersutite? or what is the difference?

thanks
avatar Re: Magnesiohornblende, Eifel Germany
December 01, 2010 05:46PM
    
Jeff,
with less exceptions (Obertiite, rock-forming amphiboles in mantle xenoliths) one cannot find any information about the composition of amphiboles from the Eifel area.
The naming convention, to call the black amphiboles from the Eifel "Ferrohornblende" and the orange-red ones "Magnesiohornblende", has developed between mineral collectors because they "want" individual names for minerals differing in their appearance. As far as I know the literature, till now there is no analytical data published referring to these black and orange-red amphiboles and we have no reference in literature for Magnesiohornblende and Ferrohornblende respectively.
Because of that during the last years various collectors started to get their material probed.
Regarding my samples (red and black ones in the scoria from different localities) the black amphibole turned out to be Kaersutite. The orange-red amphibole has a smaller content of Titanium and is in composition close to the join Kaersutite / (Fluoro)-Magnesiohastingsite.
This information was added to the locality lists.
Christof
avatar Re: Magnesiohornblende, Eifel Germany
December 01, 2010 06:56PM
Christof - thank you for the clarification and information - I will change my image caption to "amphibole group" but, could it be kaersutite as well?
avatar Re: Magnesiohornblende, Eifel Germany
December 01, 2010 07:28PM
    
Yes, it could be kaersutite.
avatar Re: Magnesiohornblende, Eifel Germany
December 01, 2010 08:31PM
Without analysis I'll leave it as amphibole, note added to image caption
Re: Magnesiohornblende, Eifel Germany
December 04, 2010 04:55PM
    
Remained 3 "magnesiohornblende" photos changed to amphibole.
Re: Magnesiohornblende, Eifel Germany
December 04, 2010 05:03PM
    
Christoph: is the ferrohornblende in [www.mindat.org] reliably analysed?
Re: Magnesiohornblende, Eifel Germany
December 04, 2010 05:07PM
    
Comment added to kaersutite page:

"Note: most kaersutites from the Eifel area (Germany) are probably not reliably identified (i.e., the identification was not based on quantitative chemical analyses and additional diffraction and spectroscopic analyses)."
avatar Re: Magnesiohornblende, Eifel Germany
December 04, 2010 11:42PM
    
Uve,

1. yes, but only quantitative chemical analyses

2. do you have new news regarding these amphiboles ?
some time ago you wrote: “Günter Blass, THE Eifel specialist, kindly asked me to write that these amphiboles are "definitely kaersutite" ".



Edited 1 time(s). Last edit at 12/05/2010 06:33AM by Christof Schaefer.
Re: Magnesiohornblende, Eifel Germany
December 05, 2010 01:45PM
    
Thanks, Christof (sorry for misspelling your first name).

2. No. I am not aware of any published EMP analyses of the amphiboles in voids. SEM-EDS is not enough for a correct ID, even with modern machines and software.
avatar Re: Magnesiohornblende, Eifel Germany
December 05, 2010 04:01PM
    
The identification of the amphiboles has been done by EMP analyses,
but they are still not published.
I have removed all my entries with unpublished references.
Hope this will help to avoid further misunderstandings.
Re: Magnesiohornblende, Eifel Germany
December 10, 2010 12:22AM
After this discussion I have reexamined the analyses, made in October 1995, from orange-brown needles from Eicher Sattel,
Andernach, Germany.

Powder XRD (thanks Thomas Felkel, Currenta, Leverkusen) corresponds with the calculated d-lines from kaersutite at
'mineralienatlas.de'.

ESD (non standardised) also corresponds the best with kaersutite: Na/K=2/ 1; Mg/Fe=8/ 1;Al/Si=1/ 3
Some measered peakheights diverges, without ZAF-correction: (Na,K)/Ca=1.1/ 2; (Mg,Fe)/Ca=4.4/ 2; Ti/Ca=0.8/ 2;
(Si,Al)/Ca=12/ 1
But as non specialist I've heard the low energy-peaks are higher, that would explain the deviation.

Greetings
Milo
Re: Magnesiohornblende, Eifel Germany
December 10, 2010 02:17PM
    
PXRD and non-standardised SEM-EDS are unfortunately not enough for an unambiguous identification of such amphiboles. But at least the data show that you might have either kaersutite or a closely related amphibole member.
Re: Magnesiohornblende, Eifel Germany
February 26, 2013 07:34AM
    
Just out of curiosity, are these now generally accepted as kaersutites?

smileys with beer

Olav
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