Symmetry statistics of mineral species in various thermodynamic conditions

Filatov S. K.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2019. V. 148. N 3. P. 1-13

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Language: Russian 


The paper generalizes data on symmetry of minerals in different Earth’s envelops as a function of temperature, pressure and combined effect of both these parameters. It is shown that distribution of mineral species in the symmetry hierarchy, in particular — existence of the monoclinic maximum and the triclinic minimum in the symmetry statistics of the world of minerals and non-organic compounds, is determined, first of all, by two diversified factors: dynamic properties of the crystal lattice (quantity of the unit cell parameters not fixed by the symmetry) and the crystal structure efficiency (maximum multiplicity of atomic positions allowed by the given point-to-point group). With increase of temperature the symmetry of the substance becomes usually higher, the permanently increasing pressure makes it lower, but rising again with its reconstruction. Mutual increase of temperature and pressure with depth inside the Earth provides the stable elevation of the average symmetry of rock — from single units up to the maximum value 48 of the Dolivo-Dobrovolsky index. Multiparametricity of the minerals symmetry statistics allows to leave without comments some fluctuations of this function until their verification by time.

Key words: symmetry, minerals, inorganic compounds, monoclinic maximum, triclinic minimum,symmetry groups, point groups of symmetry, space groups of symmetry, temperature, pressure, Earth’s envelops