In 1999, geologists made a sensational discovery in an abandoned silver mine in the Spanish province of Almería.
This is where the so-called pulpí geode is located. This is a cave filled with truly gigantic gypsum crystals. Some of them are as big as an adult human.
It is December 1999 when geologists from the University of Madrid make a spectacular discovery in the Spanish province of Almería. As the whole world prepares for the future of the year 2000, researchers find evidence of an era long past. Because in the old Mina Rica silver mine near the town of Pulpí, they come across the largest geode that has ever been found in Europe: the Pulpí geode.
The term geode defines a stone cavity containing crystals. According to the site’s official website, the pulpí geode is eight meters long and two meters high. But what is unique about this place is the size of the crystals, some of which are up to two meters long. And thus larger than most adult humans. In addition, the only place in the world where there are larger gypsum crystals than here is in the Naica Cave in Mexico. The crystals of the Pulpí-Geode are also unparalleled because of their purity and clarity. They have almost no other mineral inclusions.
How was the Pulpí geode formed?
How could such gigantic gypsum crystals even form? It was only in 2019 that scientists from the University of Granada came at least closer to solving this question. As the science website “Spektrum” reports, various factors are responsible for the growth of the pulpí geode, according to the researchers.
For example, there is the location of the Pulpí geode. It’s located underground. However, close enough to the surface to have been affected by small climatic variations in the course of their formation. The approximate age of the minerals could be determined on the basis of carbonate deposits on the gypsum crystals. They formed accordingly in a period of between two million and 60,000 years.
Geological cannibalism
The process of creating the pulpí geode itself was probably quite complex. Where the crystals are today, there used to be a primordial sea. When this dried out, the gypsum that makes up the crystals was deposited, among other things. This gypsum was then re-dissolved by the groundwater over the course of unimaginable periods of time. It finally crystallized at temperatures around 20 degrees Celsius – the “birth” of the pulpí geode.
But how could the gypsum crystals reach such a gigantic size? This is due to a type of geological cannibalism known as “Ostwald ripening”. This means nothing other than that the larger crystals became more and more powerful at the expense of the smaller ones. They literally swallowed them up. This is how the Pulpí Geode in its present form finally came about.
Marvel at the natural wonder
It was only in 2019 that the Mina Rica mine with the pulpí geode inside was opened to visitors. They climb underground via stairs and can marvel at the huge gypsum crystals from a suitable distance. A tour of one and a half hours takes guests through different galleries. Physically handicapped people are taken into the belly of the mine by an elevator.
A drop of bitterness for many tourists, however, is that photography is not permitted underground – or is reserved for the tour guides. If you want to take a souvenir snapshot home with you, you can purchase it after the tour. The operators of the cave point out that they follow all hygiene regulations in connection with the corona pandemic and that the premises are extensively disinfected several times a day.
