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The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)
  
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Cesar M. Salvan
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PostPosted: Mar 20, 2015 20:18    Post subject: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

The center-north of Portugal hosts the richest pegmatite field in the Iberian peninsula. These pegmatites occasionally have a size and composition that makes them economically viable for the exploitation of some industrial minerals. The north Portuguese pegmatites are epigenetic and hosted by granites or metamorphic rocks (shales). They are Be, Nb-Ta, P and U rich pegmatites. The Assunçao mine is a good example of this type of pegmatite. It is a beryl-columbite-phosphate pegmatite, with a primary paragenesis where the big beryl crystals, the phosphates triplite, triphyllite, apatite and isokite, the columbite-Fe and copper sulfides are prominent minerals. A strong hydrothermal phase involved mobilization of Be with formation of secondary beryl and beautiful bertrandite, and alteration of primary phosphates. The remobilized phosphate left to the formation of good autunite specimens, thanks to the uranium richness of the deposit, and other secondary phosphates. The autunite, which generally forms beautiful crystals of yellow-green color, appeared initially in the market as uranocircite. We demonstrated, by analysis of a lot of specimens, that all these lots were autunite with high probability and the geochemistry of the pegmatite do not suggest an efficient barium source.

Now, in a recent study we performed on Assunçao samples, we can report the occurrence of phurcalite, an uranyl and calcium phosphate with different structure than autunite. Rarer than autunite, the phurcalite crystallized as a previous phase in the secondary assemblage of minerals in uranium-rich pegmatites. The phurcalite occurs as small spherules composed by the radial aggregation of acicular crystals and in the form of minute tabular crystals that resembles phosphuranilite, a mineral with similar distribution of uranyl cations in its structure.

It is possible that this mineral may have gone unnoticed due to its composition, similar to autunite, but it is easily distinguishable by morphology and by structural analysis, specially vibrational spectroscopy (Raman), the best tool to recognize the mineral.

In conclusion, another mineral species to add to the long list of the Assunçao mine.



furcalita bolitas amarillas y autunita cristales verdosos.jpg
 Mineral: Phurcalite and Autunite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Description:
Phurcalite (canary yellow spherules) and autunite (yellowish green crystals) on quartz. The specimen shows clearly the difference between the two mineral species
 Viewed:  26188 Time(s)

furcalita bolitas amarillas y autunita cristales verdosos.jpg



furcalita4 FOV 2 mm.jpg
 Mineral: Phurcalite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 2 mm
 Description:
 Viewed:  26155 Time(s)

furcalita4 FOV 2 mm.jpg



autunita 10 FOV 0.8cm.jpg
 Mineral: Autunite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 0.8 cm
 Description:
 Viewed:  26205 Time(s)

autunita 10 FOV  0.8cm.jpg



phurcalite.jpg
 Description:
Raman spectrum of the Assunçao phurcalite
 Viewed:  26152 Time(s)

phurcalite.jpg



furcalita5.jpg
 Mineral: Phurcalite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1mm
 Description:
 Viewed:  26176 Time(s)

furcalita5.jpg


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Jordi Fabre
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PostPosted: Mar 21, 2015 07:40    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Superb. Thanks Dr.!
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Cesar M. Salvan
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PostPosted: Mar 22, 2015 13:12    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Thanks Jordi! A pleasure to contribute.


furcalite2.jpg
 Mineral: Phurcalite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Description:
 Viewed:  25977 Time(s)

furcalite2.jpg


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stef4412




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PostPosted: Mar 22, 2015 14:59    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Very nice
Thank a lot
It"s interesting to see phurcalite from this locality, it's changing from autunite alone
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PostPosted: Apr 16, 2015 10:37    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

More specimens to add to this interesting locality!


furcalita autunita.jpg
 Mineral: Phurcalite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 2 mm
 Description:
 Viewed:  25492 Time(s)

furcalita autunita.jpg



autunita 12.jpg
 Mineral: Autunite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1 cm
 Description:
 Viewed:  25495 Time(s)

autunita 12.jpg



2015-03-11 17.31.14.jpg
 Mineral: Phurcalite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Description:
 Viewed:  25515 Time(s)

2015-03-11 17.31.14.jpg



2014-02-18 camara 007.JPG
 Mineral: Autunite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Description:
Autunite on goethite
 Viewed:  25502 Time(s)

2014-02-18 camara 007.JPG



torbernita4.jpg
 Mineral: Metatorbernite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 5 mm
 Description:
 Viewed:  25559 Time(s)

torbernita4.jpg



Figura 1.jpg
 Mineral: Mrazekite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1.5 mm
 Description:
 Viewed:  25542 Time(s)

Figura 1.jpg



columbita-fe 2.jpg
 Mineral: Columbite-Fe
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Description:
The Assunçao pegmatites are rich in Nb. All the columbite/tantalite analyzed are clearly columbite-Fe
 Viewed:  25602 Time(s)

columbita-fe 2.jpg



torbernita.jpg
 Mineral: Torbernite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: Crystal 1.5 mm
 Description:
 Viewed:  25513 Time(s)

torbernita.jpg



autunita fluo4 copia.jpg
 Mineral: Autunite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 5 mm
 Description:
Autunite photomicrograph under UV light.
 Viewed:  25625 Time(s)

autunita fluo4 copia.jpg


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Roger Warin




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PostPosted: Apr 16, 2015 12:57    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Hi,
Many thanks. A master class with great pictures of exceptional minerals.
Roger
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PostPosted: Apr 16, 2015 20:18    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Thanks Roger!
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PostPosted: May 04, 2015 18:50    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Adding more complexity to the uranyl phosphates from Assunçao mine. The saleéite was not previously observed in the deposit, but we found very interesting specimens of saléeite-torbernite intergrown. The saleéite shows greenish yellow to green color, depending on the copper content. The torbernite forms epitaxial intergrowhts and alternating layers with saléeite. The most interesting specimens forms beautiful centimetric crystal aggregates on partially dissolved autunite or covering previous autunite crystals. Occasionally, a later autunite generation crystallized out on previous saléeite-torbernite.

So, the current count of identified uranyl phosphates described in this thread is: phurcalite, autunite, saléeite and torbernite. The observation of specimens suggests an early phurcalite deposition followed by autunite and later saléeite/torbernite. Also, the intergrowths and partially dissolved or attacked crystals suggests remobilization and recrystallization processes.

The uranyl phosphate minerals from Assunçao mine are very interesting and beautiful. Unfortunately the minerals are isostructural and practically indistinguishable de visu. Apart of torbernite, the identification of these species always require an analysis of every specimens. The Raman spectroscopy is a fast and non destructive tool to test them and we regularly used it in all samples.



torbernita asun.jpg
 Mineral: Torbernite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 5 mm
 Description:
Tabular crystals of dark green torbernite on quartz.
 Viewed:  25028 Time(s)

torbernita asun.jpg



torbernita saleeita.jpg
 Mineral: Saléeite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1.2 mm
 Description:
Saléeite and torbernite
 Viewed:  25015 Time(s)

torbernita saleeita.jpg



saleeita.jpg
 Mineral: Saléeite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1.2 cm
 Description:
 Viewed:  25074 Time(s)

saleeita.jpg



saleeita torbernita.jpg
 Mineral: Saléeite and Torbernite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1.2 cm
 Description:
Torbernite overgrown on saléeite
 Viewed:  25038 Time(s)

saleeita torbernita.jpg



torbernita saleeita2.jpg
 Mineral: Saléeite and Torbernite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1.2 cm
 Description:
 Viewed:  25194 Time(s)

torbernita saleeita2.jpg


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yowanni




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PostPosted: May 05, 2015 01:19    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

Great photos and very interesting information. Thanks for posting!!
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PostPosted: Jan 11, 2016 16:15    Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal)  

More minerals from this interesting deposit


bertandite)3 copia.jpg
 Mineral: Bertrandite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: Xtal 2 mm
 Description:
 Viewed:  22799 Time(s)

bertandite)3 copia.jpg



bertrandita2.jpg
 Mineral: Bertrandite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 5 mm
 Description:
 Viewed:  22805 Time(s)

bertrandita2.jpg



uraninita schoepita.jpg
 Mineral: Uraninite, Schoepite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 1 cm
 Description:
Uraninite with "gummites", formed by schoepite, becquerelite and an still undetermined Bi+U mineral
 Viewed:  22787 Time(s)

uraninita schoepita.jpg



2016-01-11 20-48-11 (C).jpg
 Mineral: Becquerelite
 Locality:
Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal
 Dimensions: FOV 0.5 cm
 Description:
 Viewed:  22740 Time(s)

2016-01-11 20-48-11 (C).jpg



2015-05-04_01-20-46 M=B R=6 S=4.jpg
 Mineral: Torbernite+Saléeite
 Dimensions: FOV 1 cm
 Description:
 Viewed:  22786 Time(s)

2015-05-04_01-20-46 M=B R=6 S=4.jpg


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