The Sierra del Aguilón has been the object of mining exploitation throughout history, contemporary mining begins in 1840, with the exploitation in trenches and shorts of Argentinean galena. From 1870, iron began to be extracted, which was the mining revulsive of the area, Jaravia became one of the most important mining districts in Spain. In the last decade of the 19th century, the Marín Menu family revitalized the iron holdings of the Quien tal Pensara Mine, remaining in operation for several decades, until the Civil War, thereafter the farms were abandoned. While the history of the Rica Mine that seemed forgotten, resurfaces in December 1999 with the discovery of the largest mineral geode in Europe, 20 years later the project begins to reopen the Rica Mine, so that everyone can observe the wonderful legacy left by the Pulpí miners.
From the geological heritage area, the Mina Rica, houses numerous elements of interest in addition to the giant Pulpí geode and mineralogy. From the structural point of view, the rich mine can be observed: folding, milonites, fault surfaces, etc., as well as numerous formations such as speleothems of epsomites and calcites, neoformation of minerals such as “plaster beards”, etc. The presence of siderite mineralized reefs and the differences in the lithologies of the mine are other geological elements of interest, in any case, the geological formations that stand out from the rest are the gypsum geodes; In addition to the Giant Geode, numerous geodes of different sizes can be found in the mine, with the Split Geode and the Golondrina Tail Geode the most spectacular discovered to date.
In December 1999, members of the Mineralogist Group of Madrid discovered, in the Rica Mine, the Pulpí Geode, it is a geode about 8 meters long and 2 meters high covered with huge plaster crystals. The Pulpí Geode is upholstered with plaster crystals, some of which measure almost two meters. Its transparency and conservation status make it a jewel of nature. It constitutes a unique phenomenon worldwide given its dimensions and the perfection, size and transparency of the crystals (Calaforra and García-Guinea, 2000).
The origin of this impressive geode can be explained in two phases, basically referring to the formation of the hole and the mineral deposit inside it. The hole in the rock was produced by karstification of the dolomites that form the Sierra del Aguilón, accompanied by volcanic hydrothermal injections. The mineral deposit in the geode could be explained by a mixed karst-hydrothermal model.