Giant plaster crystals

2007/04/11 Roa Zubia, Guillermo - Elhuyar Zientzia

• Geologia

Near the city of Chihuahua you will find a geological treasure: a cave filled with huge plaster crystals eleven meters long. The crystals of plaster are not so big and, therefore, geologists are surprised. However, a group of Spanish geologists has explained how they

have emerged. Above a temperature, it loses the water molecules that it has trapped by the plaster (calcium sulfate), it transforms and forms the mineral anhydrite, in short, the anhydrite itself indicates that it is a mineral without water. But the cave is below the limit temperature, very close to that limit, but below the limit. In these conditions the plaster does not lose water molecules and forms gigantic crystals.

Javier Trueba (Madrid Scientific Films)