A crystal (from greek κρúσταλλος, krýstallos,ice) is made of atoms, associated in a geometrically regular disposition that repeats itself indefinitely in the three space dimensions. Enchanting and unknown world, crystals have been object of search, collecting, study, and commerce, occupying from the beginning, a prominent position, in economic and scientific history, in the evolution of culture, art and even medicine. Crystals are the most evident expression of the intimate nature of minerals and, more generically, of matter in the solid state.

They can form in different habitats and chemical-physical conditions and they can be characterized by different speed of growth and by different reachable sizes. The time factor plays a critical role. For the formation of big crystals it’s necessary that the chemical-physical condition don’t change much, otherwise the crystal, doesn’t only quit growing, but it can even start to dissolve. Another fundamental factor is the space: it’s very unlikely that a crystal can grow without saturating the entire available surface and, therefore, without losing its connotation of crystal separated from others. Perfect crystals are the result of undisturbed and regular growth, that in rocks, may happen into hollows and clefts. You can find crystals in every type of rock and the mineralogical species, found in nature until today, are more than 4000.

Nevertheless, though the most of them crystallize, only a few can supply crystals of such a considerable dimension to be appreciated with the naked eye and only a few dozen can generate crystals able to grow items of aesthetically relevant dimensions. There is a wide range of geological habitats where crystals grow, from the deepest placed at a depth of even more than 100 km where they are included in the rocks, like diamond, to the intermediate and superficial where they grow in the rocks of crystallized hollows.

The crystals of minerals that, thanks to characteristics like resistance, hardness, good colour, high transparency and high refractive index can supply hard stones, precious and semiprecious, grow generally in the earth’s crust at a depth ranging from 3 to 12 kilometres. Crystals, at any depth they grew, after being preserved in the mother.-rock, also for a very long time, if exposed to atmospheric agents are rapidly destroyed. The show in the end, means to stir a reflection on the concept of “ subsurface ecology”. Most of the crystals in the show, actually come from exhausted mines.

It is evident how the growing demand of the world economy for energy and raw materials, is driving to a rapid and generalized exhaustion of layers and mineral resources. These last, actually, once extracted and used, can’t be reconstituted. As we know that some of the crystals in the show formed more than a billion years ago, it’s totally evident that they can’t grow, if not in another equally long time. So, as there is an ecological consciousness towards the animal and vegetable kingdom, it is necessary to awaken the public opinion also towards this category of naturalistic goods that, otherwise is threatened with extinction.