Crystallography - The Six Crystal Systems

on

SIX  CRYSTAL  SYSTEMS

WHAT IS A CRYSTAL?

    A crystal is any regular polyhedral structure bordered by smooth surfaces that a chemical compound assumes under the action of its intermolecular forces while transitioning from a liquid or gas to a solid under proper conditions. 


CRYSTAL SYSTEMS 

     Thirty-two crystal classes, which are distinguished from one another by their symmetry, are classified under six systems, each characterised by their relative length and inclinations of assumed crystallographic axes. 





1) Isometric (Cubic) System 
  •  It is one of the simplest systems and common shapes found in crystals and minerals
  • All three axes are equal in length and are mutually perpendicular to each other
  • Examples include Garnet, Cuprite, Flourite, etc. 
  • Little modifications to shapes include Octahedrons, dodecahedrons, etc. 


2) Tetragonal System 
  • It’s very similar to a cubic system, except the height is either smaller or longer
  • The base (horizontal & facial) axes are equal in length and the vertical axes are not equal
  • All three axes are mutually perpendicular
  • This system may be referred to as a rectangular prism with a square base
  • Examples include Wulfenite, Rutile, Zircon, etc. 
  • Modified shapes include Tetragonal bipyramidal, tetragonal prism, etc. 

3) Orthorhombic System 
  • All three axes have different lengths.
  • They are mutually perpendicular to each other
  • Examples include Aragonite, Sulphur, Staurolite, etc. 

4) Hexagonal System 
  • It's the largest system of all the six systems
  • It has four axes out of which three basal axes lie in the same plane and intersect at the axial cross at 120°. They all are equal in length. 
  • The fourth axis intersects the planar set of axes at right angles and is longer or shorter in length. 
  • Examples include Quartz, Hanksite, Calcite, etc. 

5) Monoclinic System 
  • All three axes are different in lengths 
  • Two axes are perpendicular to each other, while the third axis is inclined at acute angles. 
  • Examples include Gypsum, Anorthosite

6) Triclinic System
  • All axes are different in length and not mutually perpendicular to each other
  • It is the most complex system of all six systems
  • All angles are less than 90°




Comments

Post a Comment