Discovered by two miners looking for lead, the stunning white beams of gypsum have been growing at a snail’s pace for hundreds of thousands of years in caves below Naica in Mexico.

The country’s government is being urged to claim world heritage status to protect the unique formations for future generations – ten years after they were discovered.

The crystals have grown up to 11m (36ft) but it is not known why the formations fill the caves at such haphazard angles.

‘They’re really one of the wonders of the world,’ said Juanma Garcia Ruiz, a geologist from Spain’s Instituto Andaluz de Las Ciencias de la Tierra, who has studied at the mine.

‘They really are something amazing and there are still people in Mexico who don’t know how important it is to preserve them as much as possible.’

The formation of the beams 290m (950ft) below the surface, occurred when super-heated water began cooling and became saturated with gypsum.

Over time, crystals formed in the water.

One of the problems preventing the site being studied further is the heat from a nearby spring. Temperatures are so hot it is not possible to stay there for longer than ten minutes at a time.

But Prof Ruiz insists that should not mean the site is neglected, saying: ‘The crystals need to be preserved much better. Naica is very unique and the chance of having another one on the planet is very low.’