Mineralstructure

Mineralstructure refers to the arrangement of atoms in a mineral's crystalline lattice. It encompasses the geometry of the unit cell, the connectivity of constituent ions or atoms, and the symmetry described by crystal space groups. The crystal structure determines how atoms repeat in three dimensions, the coordination environment of each site, and the overall physical properties of the mineral.

The basic building block is the unit cell, which repeats to form the crystal lattice. Lattices are categorized into seven crystal systems (cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, triclinic) and further distinguished by space groups. Common structural motifs include isolated tetrahedra (e.g., olivine), single chains (pyroxenes), double chains (amphiboles), sheets (micas, clays), and three-dimensional frameworks (feldspars, quartz). Silicate minerals exhibit a wide range of structures based on SiO4 tetrahedra connectivity.

Coordination numbers, bond lengths, and polyhedral linkages influence properties such as hardness, cleavage, density, optical properties, and thermal stability. For example, framework silicates like quartz form strong 3D networks yielding high hardness and conchoidal fracture, while sheet silicates exhibit basal cleavage.

Mineralstructure is determined experimentally by X-ray diffraction, neutron diffraction, and electron diffraction, with refinements yielding lattice parameters, atomic positions, and occupancies. Structural studies support interpretation of phase transitions, polymorphism, and metamorphic transformations, and are essential in mineral identification and materials science.