kristallimuoto

Kristallimuoto refers to the external geometric shape of a crystal, determined by the internal arrangement of atoms and the symmetry of the crystal lattice. The visible form arises from the set of crystal faces that can develop under given growth conditions, and it often reflects the mineral’s internal structure.

In crystallography, crystal forms are organized according to crystal systems, which describe the possible symmetry and axes relationships. The seven systems—cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, and triclinic—give rise to characteristic habits such as cubes, octahedra, prisms, and pyramids. Faces are described by their orientations using Miller indices, which help define the spatial arrangement of a crystal’s surface.

Morphology is also categorized by habit: euhedral crystals have well-formed faces that reveal the lattice symmetry, subhedral crystals show some faces, and anhedral crystals lack visible faces. The development of crystal faces depends on growth conditions, impurities, space constraints, and interactions with neighboring crystals, all of which can truncate or modify the form.

The concept of crystal form is important for mineral identification, as the external morphology often provides clues about the internal structure. In addition, techniques such as X-ray crystallography use the arrangement of faces and lattice parameters to determine precise atomic positions. In Finnish, Kristallimuoto is commonly used to denote the general notion of crystal form in both educational and scientific contexts.