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"La Gran Geoda" in Almeria, Spain

Photo Source : Javier Garcia

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Gypsum - Gips - Plâtre - Yeso

Europe : Spain : Pilar de Jaravia : Giant gypsum geode

Coordinates : 37°24'N , 1°40'W : Mina Rica (Quien Tal Pensara mine), Pilar de Jaravia, Sierra del Aguilon, Almeria Province, Spain

There are indeed larger gypsum crystals in the world, as those in Naica, Mexico or Debar, Macedonia. However the large to giant gypsum crystals of the Pulpi Geode, Mina Rica near Pilar de Jaravia in Southeastern Spain are a prime example for an extraordinary large and textbook geode.

Crystal lined geodes are a quite common geological phenomen, particulary in volcanic rocks. The rock is cooling down and the gas content of the original melt tries to excape in small and sometimes large bubbles. Finally the rock crystallizes and the gas bubbles are trapped in the 'frozen' rock. These gas bubbles remain as more or less rounded empty voids over considerable geological times, before mineral ladden hydrothermal fluids starts to depose minerals in these vugs. Eventually crystals grow and the vug or geode fills up with well developed crystals.

Myriads of those crystal geodes exist and are often displayed and sold on mineral shops and shows. Just think of all these purple amethyst geodes from Brazil or the beautiful zeolites from the Poona - Bombay district, India. But hardly ever do geodes reach giant dimensions. In the Mina Rica they did. This once flourishing iron, lead and silver mine, which exported its mineral wealth to England and Germany, was finally closed down in the 1970s. However some miners continued to believe in the riches of the mine and eventually started exploration of the old mine workings on their own. In December 1999 they succeeded and discovered a remarkable geode...

The giant Pulpi geode, which can be accessed by a tedious trip through abandoned narrow adits and stopes only, has an inner length of 8 m and a width of 1,8 m, while the medium height is 1,7 m. Its outer appearance is that of an almost perfect elongated egg with a length of roughly 10 m. The geode is filled with water clear gypsum crystals of a medium size of 0.5 m, whereas the maximum recorded crystal size is two meters. No other minerals are known to occur, though in other parts of the mine a much more diversified mineralogy including nice celestite sprays is reported.

In the past years the 'Gran Pulpi Geoda' was investigated thoroughly by various spanish geoscientists and in fact this locality seems to be one of the best documented giant crystal occurences in existence. However it was found, that only few visitors raise the humidity in the geode from 65 % to almost 100 %, which is not good for a delicate and water soluble mineral such as gypsum. So the planned touristic exploitation of the cave was put on hold and only scientist are allowed to visit the geode for the time being.

Update July 2007 :

Courtesy of Mr. Fernandez - Cortes you are now able to read several scientific publications about the Pulpi Geode and its microclimatological problems in english language. Please click here to acess our reading room. Thank you very much.



The Pulpi Geode in a nutshell :

Mineralogy :

Gypsum without any acessory minerals

Crystal Size :

Maximum size of crystals is about 2 m, while the inner length of the geode is 8 m

Geology & Origin :

hydrothermal by sulphate rich solution

Status :

The site is protected and access is restricted to scientific parties only.

Remarks :

A prime example for a giant crystal lined geode


Other notable & famous native gypsum occurences :

Note : Gypsum is a very common mineral and even large gypsum crystals are not uncommon. There are however some outstanding occurences, namely

- The freestanding and perfect gypsum crystals of the Naica mine, Mexico, which reach 12 m length or even more. Similiar crystals are rumoured to occur at other mexican localities such as the Caverna de Santo Domingo, Santa Eulalia district.

- Giant clear gypsum crystals up to 7 m in the Debar gypsum mine Macedonia.

- Enormous crystals of gypsum are reported from the Braden and the El Teniente Mine, Chile...possibly even the largest of the world.

- Perfect Crystals up to 1 m are known to occur in the Raura mine, Lima Department, Peru.


Scientists in the gypsum geode

Photo : Javier Garcia


Schematic sketch of the geode and its dimensions

Image Source : A. Rivera



Resources and relevant weblinks :

For more information on the mineral gypsum please look at, Webmineral and the german Mineralienatlas.

There are surprisingly many publications available about this giant crystal locality, some of them very informative and extensive. Many of those are available on the net using a search engine. One of the most extensive publications in spanish is

FERNANDEZ, F.J.P; DIAZ, F.G. & CUESTA, J.M. (2000) : Pilar de Jaravia : La Geoda Gigante de la Mina Rica in : Bocamina No. 6

Other notable publications include :

CALAFORRA, J.M., GARCÍA-GUINEA, J. (2000). La Geoda Gigante de Pulpí. Boletín de la Sociedad Espaņola de Espeleología y Ciencias del Karst, Sedeck 1, 52-53.

GARCÍA-GUINEA, J., CALAFORRA, J.M. (2001). La geoda de cristales de yeso de Jaravía (Almería). Revista del Ilustre Colegio Oficial de Geólogos.

PALERO , F., GÓMEZ, F., CUESTA, J.M. (2001). Pilar de Jaravía. La Geoda Gigante de la Mina Rica. Bocamina 6, 54-67.

RIVERA, A. (2000) : La Geoda giante de la Mina Pulpi. El Pais. 10-07-00.

More publications in english can be found in the our Reading Room right here.




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