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The Mines and Minerals of Lavrion - Alumohydrocalcite

Last Updated: 9th Mar 2020

By Branko Rieck

ALUMOHYDROCALCITE, CaAl2(CO3)2(OH)4 · 4H2O, triclinic



General Appearance
In spring 2017 the author received a present of a piece of azurite and "picropharmacolite" as white sprays composed of fine acicular crystals up to 0.5 mm (see Figure 1) with a silky sheen. The minerals are grown on a schistose matrix and were found at the 3rd level of the Hilarion area by the local collector Vasilis Stergiou. The matrix and the paragenesis, however, made the identification of "picropharmacolite" highly unlikely. A PXRD-analysis revealed the true identity of alumohydrocalcite which was also confirmed by an additional EDX analysis. The chemical composition shows no elements present other than the main constituents. As can be seen in Figure 2, the similarity between picropharmacolite and alumohydrocalcite is indeed great. However, the matrix and accompanying minerals make it clear that this is a completely different type of paragenesis.

Paragenesis
On the available specimen, alumohydrocalcite rests on crusts of pale blue chalcoalumite together with azurite.

Localities
Confirmed alumohydrocalcite has so far only been discovered from a single locality at the 3rd level of the Hilarion Mine. This spot is not too far from the area yielding lavendulan and kamarizaite.


06313440015828194675934.jpg
Fig. 1: SEM micrograph (BSE mode) of a spray of acicular alumohydrocalcite crystals with lighter grey azurite crystals. SEM photograph by P. Marschner.



05131490015828194687773.jpg
Fig. 2: White sprays of alumohydrocalcite with blue azurite on schist matrix. FOV: 4 mm. This specimen is a present from Vasilis Stergiou.





Acknowledgements
Thanks go to Dr. Uwe Kolitsch for constructive comments and diligent proofreading to improve this article.

References
Rieck, B., Kolitsch, U., Voudouris, P., Giester, G. and Tzeferis, P. (2018): Weitere Neufunde aus Lavrion, Griechenland. Mineralien-Welt 29 (5), 32-77 (in German).




Article has been viewed at least 957 times.

Discuss this Article

8th Mar 2020 21:10 GMTSteve Rust Manager

Interesting read

8th Mar 2020 21:40 GMTRalph Bottrill Manager

Nice little articles Branko but would be great if we could link to these from the relevant location pages?

9th Mar 2020 10:42 GMTDavid Von Bargen Manager

02888010015837504818111.png
They already are. When you put in a locality for an article, you get the link on the locality page.

8th Mar 2020 22:42 GMTJim MGlasson

Branko
Great Job, hope you continue this work. It makes understanding the district and mineralizatrion easier for those of mus who have not had the oportunity to visit the area.

9th Mar 2020 19:52 GMTBranko Rieck Expert

@ Ralph
As David explained, all articles in this series are found at the Lavrion Mining District page (loc-1942.html).
However, you have given me an idea, that solves another problem. I will create an article, that links all articles in this series in a single place, and also keeps a running count of the changes I make to articles to accommodate new information.
For example: I recently added two new localities to the vanadinite article due to new discoveries from autumn 2019. This new information in the article may go unnoticed if it is not collected in an easily digestible way.

@ Jim
First, thank you for the nice support!
It is my intention to create articles for most if not all minerals found at the Lavrion Mining District, as well as for some notable localities, the history and the geology. For some of these I will invite guest authors to contribute.
I had long planned to write a book “The Mines and Minerals of Lavrion”. To start the matter off I created sample pages (Mixite, Sideronatrite, Vanadinite and Wulfenite) of what I wanted to do and went in search for a publisher. The result was clear: forget it! If I wanted to have the photography included the costs of this book would have been prohibitive and I also could not be sure to obtain the copyright to all the photos I wanted to use.
But the biggest problem I faced was the fact that once printed, there was no way to correct errors or to include new information.
In my discussions with many scientists and fellow collectors the idea came up to create an online-book. I do have an internet domain hosted with 1 GB of (almost unused) space, so that would solve most problems, but not the one issue of using the fantastic photos available on Mindat. Many photographers would have probably given me permission, but for sure not all.
So, Mindat articles it is, with all the infrastructure already set up and all the nice people to help and support me.
This is also as good as any the place to say thank you to Jolyon and the team to provide me with a platform that allows me to pay tribute to Lavrion, a place that has become a second home to me.

Cheers,

Branko

9th Mar 2020 21:26 GMTRalph Bottrill Manager

Thanks Brando and David
I had just looked at the location directly linked to this article, the Hilarion mine, which shows no link. But I found them now on the Lavrion page, though they are a bit lost near the bottom of the page, it would make more sense to have the articles directly linked to the Description section, or at least something to say they exist. Great idea thanks Branko.

9th Mar 2020 21:43 GMTDavid Von Bargen Manager

07027240015837902095327.png

Ralph Bottrill Manager  ✉️

though they are a bit lost near the bottom of the page
 They do show up on the "quick nav" on the right hand of the page.

10th Mar 2020 21:37 GMTRalph Bottrill Manager

Ok, but I was on the iPad with no Quicknav sadly.

10th Mar 2020 10:05 GMTKeith Compton Manager

Branko

Great articles
To me they really supplement the book - "Laurion - The Minerals in the Ancient Slags"

 
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