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Improving Mindat.orgWhewellite - Kladno, Czech Republic

13th Nov 2013 15:08 GMTChristian Auer Expert

As I got a fine specimen of whewellite from Kladno, Czech Republic recently I searched a bit our database.


I found this pic: http://www.mindat.org/photo-300486.html

In my opinion it shows whewellite but the description doesn`t! Seeing the child pic makes me think that the photographer means those small carbonate (ankerite?) xtl beeing whewellite? At least a small part of the real xtls are at the far right.


Then I found this one: http://www.mindat.org/photo-73355.html

In my opinion it also shows some carbonate or even two different?


This one http://www.mindat.org/photo-66907.html seems ok as does http://www.mindat.org/photo-376735.html.


Just my opinion but whewellite isn`t really something I handle every day.

13th Nov 2013 15:26 GMTChristian Auer Expert

-- moved topic --

13th Nov 2013 17:38 GMTReiner Mielke Expert

I agree with Christian they show some sort of carbonate not Whewellite.

13th Nov 2013 18:59 GMTMartin Rich Expert

I'm sure the 2nd pic is a carbonate - typical rhombohedron. This shape is not possible for Whewellite (2/m).

13th Nov 2013 19:45 GMTAlfredo Petrov Manager

The first pic shows big opaque whewellite crystals on the right hand edge. The description is wrong - Photographer focussed on the tiny drusy ankerites instead of the big whewellites.

14th Nov 2013 07:37 GMTUwe Ludwig

I agree with Alfredo. The whewellite of the respective specimen is not in the focus. The whewellie of this location is yellow as these crystalls which can be seen at the right side.


Rgds.

Uwe Ludwig

14th Nov 2013 09:49 GMTChristian Auer Expert

Give me 2-3 weeks then I`ll make a pic and SEM-EDS analysis of my specimen.


Took already 4 samples for EDS: 1) from the whewellite, 2) a powdery white mass (dickite?) coating some carbonate, 3) white rhombs and 4) brown xtls similiar to those from http://www.mindat.org/photo-73355.html (most likely siderite).


I`ll let you know the results but as mentioned it will need a time ...

11th Dec 2013 13:39 GMTChristian Auer Expert

Ok today I had some time to ID the material. Here is the result:

http://www.mindat.org/photo-577980.html


I also found a single xtl on the specimen shown on pic 3 which is not possible to ID without destroying it.

11th Dec 2013 18:11 GMTUwe Kolitsch Manager

"Ankerite: Ca 2,4 : Fe 0,9 : Mg 1,6"

That's Fe-bearing dolomite, not ankerite.

11th Dec 2013 19:19 GMTAlfredo Petrov Manager

Some mineralogist once claimed that all so-called "ankerites" from its classic localities were Fe-rich dolomites, and that true ankerite in the modern mineralogical sense of Fe-dominance could only exist in igneous carbonatite rocks? Perhaps I'm mis-remembering this.

12th Dec 2013 10:22 GMTChristian Auer Expert

Thanks Uwe, thats the result when you make an interpretation and are already under the influence what you want to read ;-)
 
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