Correlations between chemical and structural complexities of minerals were analysed using a total of 4962 datasets on the chemical compositions and 3989 datasets on the crystal structures of minerals. The amounts of structural and chemical Shannon information per atom and per unit cell or formula unit were calculated using the approach proposed by Krivovichev with no H-correction for the minerals with unknown H positions. Statistical analysis shows that there are strong and positive correlations (R-2 > 0.95) between the chemical and structural complexities and the number of different chemical elements in a mineral. Analysis of relations between chemical and structural complexities provides strong evidence that there is an overall trend of increasing structural complexity with the increasing chemical complexity. Following Hazen, four groups of minerals were considered that represent four eras of mineral evolution: "ur-minerals", minerals from chondritic meteorites, Hadean minerals, and minerals of the post-Hadean era. The analysis of mean chemical and structural complexities for the four groups demonstrate that both are gradually increasing in the course of mineral evolution. The increasing complexity follows an overall passive trend: more complex minerals form with the passage of geological time, yet the simpler ones are not replaced. The observed correlations between the chemical and structural complexities understood in terms of Shannon information suggest that, at a first approximation, chemical differentiation is a major force driving the increase of complexity of minerals in the course of geological time. New levels of complexity and diversification observed in mineral evolution are achieved through the chemical differentiation, which favours local concentrations of particular rare elements and creation of new geochemical environments.

Single-crystal X-ray diffraction data have been obtained for crystals of the F analog of superhydrous phase B, Mg10Si3O14F4. Twinned crystals were synthesized using a split-sphere anvil apparatus (USSA-2000) at pressures between 17.8 and 22.3 GPa and temperatures between 1450 and 1600 degrees C, Orthorhombic (space group Pnnm) unit-cell parameters are a = 5.050(3), b = 13.969(2), and c = 8.640(3) Angstrom. The substitution of F for H results in minor crystal chemical changes. Notably, average Mg-F distances (1.95 Angstrom) are shorter than the corresponding average of Mg-OH distances (1.98 Angstrom). These differences are reflected in shortening of unit-cell axes a and c in superfluorous B by 0.6 and 0.8%, respectively, relative to superhydrous B, while the b axis is unchanged. The close similarities between superhydrous and superfluorous B phases suggest that F will usually substitute for OH- in mantle phases.

Single-crystal X-ray diffraction data have been obtained for synthetic Fe-Mg silicate spinels, gamma-(MgxFe1-x)2SiO4 (x = 1.00, 0.40, and 0.20). The measurements on gamma-Mg2SiO4 synthesized at 20 GPa and 1400-degrees-C, compared with previous data on a specimen synthesized at 22 GPa and 1000-degrees-C, provide evidence that approximately 4% of Si(tot), enters octahedral coordination in the sample synthesized at higher temperature. Fe-bearing silicate spinels synthesized at lower pressures display no evidence for Fe-Si disorder.

Structural and volume compressibility data for reedmergnerite, NaBSi3O8, were obtained by single-crystal X-ray diffraction at pressures up to 4.7 GPa. The bulk modulus was determined to be 69.8(5) GPa with the pressure derivative constrained to 4. Unit-cell compression is anisotropic, as indicated by unit strain tensors. Tetrahedral bond lengths and angles remained relatively constant over the pressure interval, whereas Na-O bonds decreased systematically. T-O-T angles underwent a variety of behaviors, remaining constant or decreasing with pressure.

Crystals of BaSi4O9 synthesized at 4 GPa and 1000 degrees C were determined to be isostructural with barium tetragermanate [trigonal, space group P3, a =11.2469(11) and c = 4.4851(6) Angstrom, V = 491.3(1) Angstrom(3)]. The structure (R = 2.4%) features a corner-linked framework of three-member silicate tetrahedral rings, which are cross-linked by isolated silicate octahedra. Ba cat-ions occupy tenfold-coordinated sites in channels defined by the silicate framework. This structure is 4.2% denser than the topologically similar benitoite form of high-pressure BaSi4O9, which was produced by grinding the barium tetragermanate-type crystals described in this report.

Structural and volume compressibility data for low albite were obtained by single-crystal X-ray diffraction methods at pressures up to approximately 4 GPa. The bulk modulus was determined to be 54(1) GPa, with a pressure derivative of 6(1). Unit cell compression is anisotropic, as indicated by unit strain tensors. In the softest direction, approximately perpendicular to (100), the structure is three times more compressible than in the stiffest direction. Intensity data were collected, and structures were refined at 0.00, 0.44, 1.22, 2.68, and 3.78 GPa. With increasing pressure, (1) the volumes of the TO4 tetrahedra do not vary, (2) the volume of the NaO7 polyhedron varies linearly with the volume of the unit cell, and (3) Si-O-Si angles increase or remain constant, but only Al-O-Si angles decrease, which is consistent with the smaller force constant of the Al-O-Si vs. Si-O-Si angle. We conclude that compression is accomplished through the bending of Al-O-Si angles, which squeezes together the chains of four-membered rings that run parallel to [001] and that are separated by zigzag channels containing Na atoms. The feldspar three-dimensional tetrahedral framework can be considered to be made up of these chains, which are linked together by O(c)-type atoms. The average value of the T-O(c)-T angle correlates with bulk moduli of alkali feldspars. Al-Si disorder tends to stiffen the T-O(c)-T angle in high albite, which in turn decreases the compressibility and thus can serve as a mechanism for pressure-dependent ordering of high to low albite.

A single crystal of intermediate orthopyroxene, (Mg0.56Fe0.44)2Si2O6, has been recovered from a synthesis experiment at approximately 1.1 GPa and 1600-degrees-C. This rapidly quenched crystal displays a high degree of disorder for orthopyroxene M1 and M2 octahedral sites (K(d) = 3.9). Comparison with low-pressure orthopyroxene quenched from similar temperatures indicates that pressures corresponding to the Earth's mantle transition zone have little effect on Mg-Fe ordering between M1 and M2, unlike intracrystalline ordering in several other dense magnesium iron silicates.