Mineralrichtungen

Mineralrichtungen are directions defined within a crystal lattice that describe how characters of the crystal extend in space. They express the orientation of the internal lattice and are fundamental for understanding crystal shape, growth, and anisotropic properties. In crystallography, directions refer to lines through the crystal and are used to specify how properties or features vary with direction.

Notation and concepts are standardized. Directions are written with square brackets [uvw], where u, v, w are integers describing a vector along the crystal’s unit-cell axes. Families of such directions related by the crystal’s symmetry are indicated with angle brackets <uvw>. Planes are denoted by parentheses (hkl) and their symmetry-related families by braces {hkl}. This notation allows concise description of a crystal’s geometry and the orientation of features such as growth directions, defects, or cleavage planes.

Common directions correspond to the primary crystallographic axes, such as [100], [010], and [001] in many systems, as well as diagonal directions like [110] or [111]. In hexagonal crystals, the c-axis is typically along [001]. These directions influence how minerals form, fracture, and respond to external stimuli, including mechanical stress and optical fields.

Applications include describing cleavage directions, growth habits, and the anisotropy of physical properties such as hardness, refractive indices, and elasticity. They are determined experimentally through techniques such as X-ray diffraction, electron diffraction, and polarized light microscopy, which reveal the orientation of the crystal lattice relative to observed features.

In summary, Mineralrichtungen provide a precise language for expressing how crystal structure governs the visible and measured properties of minerals.