Crystals

Crystals are solid substances that have a natural external shape of regular symmetrical polyhedra based on their internal structure, that is, on one of several certain regular arrangements of matter constituents (atoms, molecules, ions). The particles forming this solid matter form a crystal lattice. If the crystals are heated to their melting point, they begin to melt. Well, what happens if you slowly cool the liquid melts to the same temperature? It is clear that, after cooling to the melting point, the liquid melt will begin crystallize. Hence, the melting temperature of crystals of this substance is at the same time the crystallization temperature of its melt.

Crystals are solid substances that have a natural external shape of regular symmetrical polyhedra based on their internal structure, that is, on one of several certain regular arrangements of matter constituents

How do crystals grow in the melt? In the mass of the solidifying melt, many crystalline embryos are formed at once; all of them simultaneously grow into small crystals. While these crystals are very small, they grow freely, each - the right polyhedron. But, increasing, the crystals meet and begin to interfere with each other. As soon as two growing crystals meet each other, the growth of both crystals in this place ceases: no one of them can move back. On the other hand, where the crystals have not yet collided with their neighbors, they continue to grow. So it turns out that crystals grow in one direction more than in others: wrong polyhedra are formed, and the crystalline grains from which the rocks. Or, in the end, after a persistent "struggle" individual crystals survive.

Why do we say that crystals are characterized by their multifaceted form? First of all, because if this same crystal grain grew not in cramped state, but so that nothing hindered it, then it would inevitably take the form of a regular polyhedron. A curve, not a multi-faceted form, is not a natural, but a forced form of a crystal: he had to accept it because there was no place or material for the formation of a true regular shape characteristic of all crystals growing without interference. If the crystals grow freely - then the correct symmetrical polyhedra will again appear in front of you. And most importantly, because the internal structure, regularity, periodicity, symmetry of the arrangement of atoms did not change from the fact that the form was violated.

Therefore, real crystals always contain various defects of the internal structure, distortions and unevenness at the faces and have a lower symmetry of the polyhedron due to the specific conditions of growth, inhomogeneity of the supply medium, damage and deformation. Real crystals do not necessarily have crystallographic faces and a regular shape, but they retain the main property - the regular position of the atoms in the crystal lattice.

The largest crystals were discovered in 2000 in the Cave of Crystals in the Nike mine, in the Mexican state of Chihuahua. Some of the gypsum crystals found there reach 15 meters in length, and in width - 1 meter.

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