Growth of crystals

The growth of crystals and the mechanism of formation of aggregates from them in many respects is essentially different. Therefore, consider the growth of crystals from the point of view from simple to complex.

The growth of crystals and the mechanism of formation of aggregates from them in many respects is essentially different

With the growth of flat layers, atoms, ions or crystal molecules are deposited on the faces in such a way that they lie parallel to the base, that is, the corresponding face. One layer is superimposed next, another one on it, etc. It turns out something like a stack of paper sheets. But the layers may not be flat, but spiral. Spirals are found on crystals of diamond, hematite, ilmenite, pyrite and other minerals.

The growth of crystals by zones (zonal growth) is the appearance on the entire surface of the crystal of closed layers concentrically overlapping each previous layer. Something like this will happen if the cube is consistently covered with layers of paint. Each such volumetric zone (shell) was formed at a certain time of crystallization. If the conditions change during the growth of the crystal, each of them will have different properties: color, thickness, number of inclusions, composition, etc. As a result, the crystal gets a zonal structure, usually perfectly visible to the naked eye in transverse cleavages or cuts.

Sectorial growth of crystals is manifested in the case when different faces of the crystal have different physical and chemical properties. For example, some faces easily absorb the impurity, while others, on the contrary, vigorously repel it. Hence, the pyramids of the growth of the faces will have unequal properties, manifested in the form of a sectorial structure of the crystal. A pyramid of growth is a spatial "trace" of the movement of the corresponding face during the growth of the crystal. The crystal appears to be composed of pyramids, the bases of which are its faces.

The mosaic growth of crystals is due to the appearance of inhomogeneities, defects in the crystal lattice of the mineral. Atoms make "mistakes", omissions, capture the smallest solid particles or gas-liquid bubbles. In this case, an imperfect crystal grows, consisting of blocks that are turned to each other at a small angle. It resembles a box with carelessly folded cubes.