Variety of Free Crystal Shapes

Abstract

The diversity of free crystal shapes in nature is statistically described by the coefficient of variation in the central distances to symmetrically equivalent faces of simple crystallographic forms present on the crystal. The coefficient of variation for natural crystals lies in a limited range of values from 0.02 to 0.2. This regularity, implemented during growth, dissolution, and in the equilibrium state, is accompanied by a number of natural phenomena, which is explained by the fluctuation model of crystal growth. An increase in the coefficient of variation leads to temperature rise; nonstationarity of the process; and dissymmetrizing phenomena, which include gravitational field, anisotropy of facet supply, and geometry of free space. A decrease in the coefficient of variation causes prolonged growth or dissolution and symmetrization effects, which manifest themselves under the complex influence of several factors, including mechanical impacts on the crystal.