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Cesar M. Salvan
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Posted: Mar 20, 2015 20:18 Post subject: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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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.
Mineral: | Phurcalite and Autunite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Phurcalite (canary yellow spherules) and autunite (yellowish green crystals) on quartz. The specimen shows clearly the difference between the two mineral species |
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![furcalita bolitas amarillas y autunita cristales verdosos.jpg](files/thumbs/t_furcalita_bolitas_amarillas_y_autunita_cristales_verdosos_209.jpg)
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Mineral: | Phurcalite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 2 mm |
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26653 Time(s) |
![furcalita4 FOV 2 mm.jpg](files/thumbs/t_furcalita4_fov_2_mm_317.jpg)
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Mineral: | Autunite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 0.8 cm |
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26709 Time(s) |
![autunita 10 FOV 0.8cm.jpg](files/thumbs/t_autunita_10_fov_08cm_552.jpg)
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Raman spectrum of the Assunçao phurcalite |
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26651 Time(s) |
![phurcalite.jpg](files/thumbs/t_phurcalite_160.jpg)
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Mineral: | Phurcalite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1mm |
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26677 Time(s) |
![furcalita5.jpg](files/thumbs/t_furcalita5_436.jpg)
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Jordi Fabre
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Posted: Mar 21, 2015 07:40 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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Superb. Thanks Dr.!
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Cesar M. Salvan
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Posted: Mar 22, 2015 13:12 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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Thanks Jordi! A pleasure to contribute.
Mineral: | Phurcalite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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26478 Time(s) |
![furcalite2.jpg](files/thumbs/t_furcalite2_640.jpg)
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stef4412
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Posted: Mar 22, 2015 14:59 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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Very nice
Thank a lot
It"s interesting to see phurcalite from this locality, it's changing from autunite alone
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Cesar M. Salvan
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Posted: Apr 16, 2015 10:37 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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More specimens to add to this interesting locality!
Mineral: | Phurcalite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 2 mm |
Description: |
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25995 Time(s) |
![furcalita autunita.jpg](files/thumbs/t_furcalita_autunita_149.jpg)
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Mineral: | Autunite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1 cm |
Description: |
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25992 Time(s) |
![autunita 12.jpg](files/thumbs/t_autunita_12_107.jpg)
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Mineral: | Phurcalite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Description: |
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26011 Time(s) |
![2015-03-11 17.31.14.jpg](files/thumbs/t_2015_03_11_173114_690.jpg)
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Mineral: | Autunite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Description: |
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26000 Time(s) |
![2014-02-18 camara 007.JPG](files/thumbs/t_2014_02_18_camara_007_182.jpg)
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Mineral: | Metatorbernite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 5 mm |
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26055 Time(s) |
![torbernita4.jpg](files/thumbs/t_torbernita4_213.jpg)
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Mineral: | Mrazekite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1.5 mm |
Description: |
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26040 Time(s) |
![Figura 1.jpg](files/thumbs/t_figura_1_280.jpg)
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Mineral: | Columbite-Fe |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Description: |
The Assunçao pegmatites are rich in Nb. All the columbite/tantalite analyzed are clearly columbite-Fe |
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26097 Time(s) |
![columbita-fe 2.jpg](files/thumbs/t_columbita_fe_2_175.jpg)
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Mineral: | Torbernite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | Crystal 1.5 mm |
Description: |
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26010 Time(s) |
![torbernita.jpg](files/thumbs/t_torbernita_290.jpg)
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Mineral: | Autunite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 5 mm |
Description: |
Autunite photomicrograph under UV light. |
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26124 Time(s) |
![autunita fluo4 copia.jpg](files/thumbs/t_autunita_fluo4_copia_132.jpg)
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Roger Warin
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Posted: Apr 16, 2015 12:57 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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Hi,
Many thanks. A master class with great pictures of exceptional minerals.
Roger
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Cesar M. Salvan
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Posted: Apr 16, 2015 20:18 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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Thanks Roger!
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Cesar M. Salvan
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Posted: May 04, 2015 18:50 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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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.
Mineral: | Torbernite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 5 mm |
Description: |
Tabular crystals of dark green torbernite on quartz. |
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25525 Time(s) |
![torbernita asun.jpg](files/thumbs/t_torbernita_asun_159.jpg)
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Mineral: | Saléeite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1.2 mm |
Description: |
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25514 Time(s) |
![torbernita saleeita.jpg](files/thumbs/t_torbernita_saleeita_141.jpg)
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Mineral: | Saléeite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1.2 cm |
Description: |
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25580 Time(s) |
![saleeita.jpg](files/thumbs/t_saleeita_745.jpg)
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Mineral: | Saléeite and Torbernite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1.2 cm |
Description: |
Torbernite overgrown on saléeite |
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25542 Time(s) |
![saleeita torbernita.jpg](files/thumbs/t_saleeita_torbernita_194.jpg)
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Mineral: | Saléeite and Torbernite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1.2 cm |
Description: |
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25692 Time(s) |
![torbernita saleeita2.jpg](files/thumbs/t_torbernita_saleeita2_730.jpg)
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yowanni
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Posted: May 05, 2015 01:19 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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Great photos and very interesting information. Thanks for posting!!
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Cesar M. Salvan
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Posted: Jan 11, 2016 16:15 Post subject: Re: The phurcalite from Assunçao mine (Ferreira de Aves, Satao, Portugal) |
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More minerals from this interesting deposit
Mineral: | Bertrandite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | Xtal 2 mm |
Description: |
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23302 Time(s) |
![bertandite)3 copia.jpg](files/thumbs/t_bertandite3_copia_120.jpg)
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Mineral: | Bertrandite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 5 mm |
Description: |
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23306 Time(s) |
![bertrandita2.jpg](files/thumbs/t_bertrandita2_175.jpg)
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Mineral: | Uraninite, Schoepite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 1 cm |
Description: |
Uraninite with "gummites", formed by schoepite, becquerelite and an still undetermined Bi+U mineral |
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23290 Time(s) |
![uraninita schoepita.jpg](files/thumbs/t_uraninita_schoepita_159.jpg)
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Mineral: | Becquerelite |
Locality: | Senhora da Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu District, Portugal | ![](templates/FabreMinerals/images/LocalidadesGreen.png) |
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Dimensions: | FOV 0.5 cm |
Description: |
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23237 Time(s) |
![2016-01-11 20-48-11 (C).jpg](files/thumbs/t_2016_01_11_20_48_11_c_402.jpg)
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Mineral: | Torbernite+Saléeite |
Dimensions: | FOV 1 cm |
Description: |
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23289 Time(s) |
![2015-05-04_01-20-46 M=B R=6 S=4.jpg](files/thumbs/t_2015_05_04_01_20_46_mequalb_requal6_sequal4_752.jpg)
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