We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences

FMF English Forum is moderated by John S. White and Peter Megaw

Spanish message board

Newest topics and users posts
23 Feb-23:54:01 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:46:53 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:41:27 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:36:00 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:26:50 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:22:59 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:20:11 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-23:14:34 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-22:54:15 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-22:47:40 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-22:42:24 Re: the joy of tucson, 2020 gail spann experience (Gail)
23 Feb-17:14:59 Re: celestine (Bob Harman)
23 Feb-17:11:41 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
23 Feb-14:13:03 Tucson show 2020 - the new discoveries! (2) (Jordi Fabre)
23 Feb-13:52:44 Tucson show 2020 - the new discoveries! (1) (Jordi Fabre)
23 Feb-13:01:53 Re: taking great photographs (Jesse Fisher)
23 Feb-12:27:14 Re: taking great photographs (Jordi Fabre)
23 Feb-12:14:45 Re: presentation of new members - from saskatoon, saskatchewan, canada (Don Lum)
23 Feb-10:53:06 Re: taking great photographs (Le Snelling)
23 Feb-09:08:19 Re: presentation of new members - from saskatoon, saskatchewan, canada (Firmo Espinar)
23 Feb-08:54:52 Presentation of new members - from saskatoon, saskatchewan, canada (Fstr N U)
23 Feb-06:37:51 Re: taking great photographs (Basti)
22 Feb-21:46:04 Re: taking great photographs (Marvinlewinsky)
22 Feb-21:11:53 Re: taking great photographs (Pete Richards)
22 Feb-20:38:31 Re: don lum collection (Don Lum)

For lists of newest topics and postings click here


View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  


The time now is Feb 23, 2020 23:57

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
Pyrite from Ambasaguas, La Rioja, Spain
  Index -> The Ten Thousand Club

View previous topic :: View next topic  
Author Message

Joan R.

Joined: 16 Mar 2007
Posts: 75
Location: Barcelona

Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jan 03, 2008 11:45    Post subject: Pyrite from Ambasaguas, La Rioja, Spain  

If we are thinking on a short list of worldwide famous mineral deposits in Spain, the pyrites from La Rioja-Soria (Northern Spain) stand out among the most significant and spectacular places. Its peculiarity lies in the beauty of the crystals and the richness of its different habitus, which depends on the outcrop area, all in the Cretaceous lutites and sandstones. So, it is well-known the perfection of cubes from Navajún and Valdeperillo (Córnago) and pentagonododecahedral (pyritohedral) crystals and pine cones from Ambasaguas (comprising a wide area). Other less known localities, but not less interesting are the towns of Aguilar del Río Alhama and Cervera del Río Alhama in La Rioja region side and San Pedro Manrique - Valdenegrillos in the Soria province side.

Ambasaguas is a small town located at 6 km from Muro de Aguas, in La Rioja region. Seeing the large number of sources of crystalline water in Muro de Aguas (waters wall) central square, we could understand the town name’s origin. Nowadays, old Ambasaguas inhabitants resides in Muro de Aguas.
The casual extraction of pyrite by the locals dates from many decades ago. Probably they had been extracting pyrites due to its brilliant faces, magic beliefs or, in the last years, for mineral collectors. They told me that many big pyrites were used as sling projectiles (a sling is a projectile weapon typically used to throw a blunt projectile such as a stone. It is also known as the shepherd's sling) to scare away wild beasts which attacked the herds. It was not until 1966 when the pyrite mining was carried out in an ordered way oriented to get collection specimens. Currently the mine is working under the name "Ambasaguas-II Mine", with the corresponding exploitation rights property of Piritas de Ambasaguas S.L.

The pyrite mineralization is related with the hydrothermal metamorphism that took place in this area. The formation of pyrite crystals may be explained by the reaction of iron from the lutitic sediments (containing iron oxides and chlorite), with the sulfur from sedimentary pyrite thermal decomposition or thermo chemical reduction of the sedimentary sulfates. The pyrite appears in the lutitic levels, always in contact with roof layers of sandstone. This roof levels acted as aquifers during metamorphism transporting hot rich sulphur fluids. The rich pyrite crystal habitus diversity is related to the availability of sulphur in these sediments. (1)
You could see all around of Ambasaguas some galleries and small quarries where, during many years, worldwide mineral collectors have been looking for pyrites. Nowadays you must to ask permission to the owners.
In the below attached image you can see some pyrite habitus that occurs in the mined areas. We would like to emphasize in specimens like pure pyritohedron, cube-pyritohedron combinations, cubes with octahedral faces, deformed pyritohedrons... some of them with beveled edges, with or without striated faces.

The crystals of Ambasaguas and Navajún remain among the most beautiful and perfect pyrite specimens in the world, and thanks to the dedication of the mines owners, we will continue collecting and enjoying their capricious forms.

(1) Rodas M., Alonso-Azcárate, J., Mas J.R., Bottrell S.H. (2002): Los yacimientos de pirita de la Cuenca de Cameros. Zubía, Nº 14, pags. 173-190.
(2) Alonso-Azcárate, J., Rodas, M., Fernández-Díaz, L., Bottrell, S.H., Mas, J.R.,López-Andrés, S. (2001): Causes of variation in crystal morphology in metamorphogenic pyrite deposits of the Cameros Basin (N Spain). Geological Journal, Volume 36, Issue 2 , Pages 159-170.
(3) García, G, Alonso-Azcárate, J. (2003): Piritas de Ambasaguas. Bocamina, Nº 12, pag. 13-45. https://www.bocamina.com/esp/n12/portada.pdf

Mine & locality images: https://mti-minas-rioja.blogspot.com/

Ambasaguas Pyrite Map.jpg
 Viewed:  34264 Time(s)

Ambasaguas Pyrite Map.jpg

Pyrite Ambasaguas crystal structure.jpg
 Viewed:  34318 Time(s)

Pyrite Ambasaguas crystal structure.jpg

Pyrite Ambasaguas 1.jpg
 Viewed:  34201 Time(s)

Pyrite Ambasaguas 1.jpg

Pyrite Ambasaguas NH12K7.jpg
Pine cone formed by small cubic crystals modified by pentagonododecahedron (pyritohedral) faces on the typical Ambasaguas matrix. Ambasaguas 1 Mine, Ambasaguas(1994). 6 x 4.2 x 4.1 cm
 Viewed:  34247 Time(s)

Pyrite Ambasaguas  NH12K7.jpg

Pyrite Ambasaguas L14DAI0f.jpg
The crystals have one of the more classical combinations of forms from Ambasaguas, the cube and the pyritohedron, the first delicately striated. Mina Ambasaguas 1, Ambasaguas (1992). 11 x 10.8 x 5.8 cm
 Viewed:  34213 Time(s)

Pyrite Ambasaguas L14DAI0f.jpg

Pyrite Ambasaguas NA57K7.jpg
Pyritohedral crystals of Pyrite, one of them clearly dominant. Ambasaguas 1 Mine, Ambasaguas(1994). 3.6 x 3 x 2.9 cm
 Viewed:  34252 Time(s)

Pyrite Ambasaguas  NA57K7.jpg

Joan Rosell
Grup Mineralògic Català
Back to top
Reply to topic Reply with quote
Display posts from previous:   
   Index -> The Ten Thousand Club   All times are GMT - 5 Hours
Page 1 of 1

Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum

All pictures, text, design © Forum FMF 2006-2020

Powered by FMF