rhombohedral
Adjective: - Having threefold symmetry; specifically in crystallography, describing a crystal system or lattice structure where the three axes are of equal length and intersect at equal angles that are not right angles (90°). This is a subdivision of the hexagonal crystal system.
- Used primarily in scientific contexts, especially in crystallography, mineralogy, and solid-state physics, to describe the shape and internal structure of crystals.
- It describes a specific geometric arrangement where the unit cell is shaped like a rhombohedron (a six-sided prism with each face being a parallelogram).
Scientific Description:
- Calcite is a common mineral with a rhombohedral crystal structure.
- The rhombohedral phase of the material was confirmed using X-ray diffraction.
Mathematical/Geometric Description:
- A rhombohedral lattice can be seen as a distorted cube.
- The atoms are arranged in a rhombohedral unit cell.
"Rhombohedral system": A crystal system characterized by a rhombohedral unit cell. It is often considered a special case of the hexagonal system.
- Quartz can crystallize in the trigonal system, which is often grouped with the rhombohedral system.
"Rhombohedral cleavage": A type of breakage in minerals where the fragments have rhombohedral shapes.
- The rhombohedral cleavage of calcite is very distinctive.
Rhombohedron (noun): A three-dimensional geometric figure with six faces, each of which is a rhombus.
- The crystal was a perfect rhombohedron.
Trigonal (adjective): Often used synonymously or in a closely related context in crystallography to describe crystals with threefold symmetry about a major axis. The rhombohedral lattice is a type of trigonal lattice.
- The trigonal crystal class includes both rhombohedral and hexagonal shapes.
- Trigonal (in specific crystallographic contexts, though nuances exist).
- Equiangular (in a very general geometric sense, but not a direct synonym as it lacks the specific threefold symmetry implication).
- having threefold symmetry