Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types:
- Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. Mineralogy is an Earth Science focused around the Chemistry, Crystal structure, and physical (including optical) properties of Minerals This occurs quite easily in graphite, making the material feel slippery. The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon.
- Cubic cleavage: cleavage parallel to the faces of a cube. A cube is a three-dimensional solid object bounded by six square faces facets or sides with three meeting at each vertex. This is the source of the cubic shape seen in crystals of ground table salt (sodium chloride). Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants
- Diagonal cleavage: cleavage parallel to a diagonal plane.
- Lateral cleavage: cleavage parallel to the lateral planes.
- Octahedral, Dodecahedral, or Rhombohedral cleavage: cleavage parallel to the faces of an octahedron, dodecahedron, or rhombohedron (respectively). An octahedron (plural octahedra is a Polyhedron with eight faces A dodecahedron is any Polyhedron with twelve faces but usually a regular dodecahedron is meant a Platonic solid composed of twelve regular Pentagonal See also Rhombohedral - Crystal system Octahedral cleavage is seen in common semiconductors (see below). A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that
- Prismatic cleavage, cleavage parallel to a vertical Prism. A prismatic surface is a surface generated by all the lines that are parallel to a given line and intersect a broken line that is not in the same plane as the given line General right and uniform prisms A right prism is a prism in which the joining edges and faces are perpendicular to the base faces
This is of technical importance in the electronics industry and in the cutting of gemstones. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical A gemstone or gem, also called a precious or semi-precious stone, is a piece of attractive Mineral, which &mdash when cut and polished &mdash While precious stones are generally cleaved by impact, man-made single crystals of semiconductor materials are generally sold as thin wafers which are much easier to cleave. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that A wafer is a thin slice of Semiconductor material such as a Silicon crystal used in the fabrication of Integrated circuit and other microdevices Simply pressing a silicon wafer against a soft surface and scratching its edge with a diamond scribe is usually enough to cause cleavage; however, when dicing a wafer to form chips, a procedure of scoring and breaking is often followed for greater control. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in Elemental semiconductors (Si, Ge, and diamond) are diamond cubic, a space group for which octahedral cleavage is observed. Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 The diamond cubic Crystal structure is a repeating pattern that atoms may adopt as certain Materials solidify The space group of a Crystal or crystallographic group is a mathematical description of the Symmetry inherent in the structure This means that some orientations of wafer allow near-perfect rectangles to be cleaved. Most other commercial semiconductors (GaAs, InSb, etc. Gallium arsenide ( GaAs) is a compound of two elements Gallium and Arsenic. Indium antimonide ( is a Narrow gap Semiconductor material from the III - V group used in Infrared detectors including Thermal ) can be made in the related zinc blende structure, with similar cleavage planes. Sphalerite (( Zn, Fe) S) is a Mineral that is the chief Ore of Zinc.
See also
References
- Hurlbut, Cornelius S. Cleavage, in Geology and related disciplines describes the tendency of a Mineral or rock to break along preferred planes of weakness ; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed. , Wiley, pp. 200 - 202, ISBN 0-471-80580-7
- Mineral galleries: Mineral properties - Cleavage
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