The characteristics of crystal faces that defines the crystal systems are the angles between the crystal faces.
Crystal faces intersects at specific angles to one another and this defines a crystal system. This angle is constant for all crystals that belongs to the same system. This is the Steno's law of Interfacial angles.
The crystal systems are cubic, tetragonal, orthorhombic, trigonal, hexagonal, monoclinic, and triclinic.
A crystal is a solid whose structure have an ordered long range arrangement which permeates in the solid.
The angles between corresponding crystal faces are constant. Diamond falls into the Isometric System but not all diamonds form in cubes with faces at 90 degrees. For example an octahedron has eight faces four meeting at a point above and four below. The faces are not at 90 degrees.
A crystal form can be expressed in relation to a group of planar faces which are geometrically equal in angle and which also possesses spatial positions in relation to each other by a certain group of symmetry operations. This angle is the same for all crystals as explained in the Steno's law of Interfacial angles.
Each and every crystal set can be categorized into one of six crystal systems. These entails the isometric, hexagonal, tetragonal, orthorhombic, monoclinic, and triclinic systems.
The part of the peripheral nervous system (PNS) neuroglia that form the myelin sheaths around larger nerve fibers in the PNS would be the Schwann cells. The most important function is to myelinate the axons found in the PNS. Myelin aids in the increase of the saltatory conduction of a neuron.
