The crystal structure is said to be isotropic if the spacing of the atoms is the same along each axis. If the spacing or arrangement of atoms along one axis is different from that of another axis, then the crystal is said to be anisotropic . If the atoms or molecules of a solid are not arranged in a regular periodic structure, then the solid is said to be amorphous . Glass and plastic are examples of amorphous solids, table salt is an example of an isotropic crystal, and snowflakes or calcite are examples of anisotropic crystals. This pattern is predictable and can be manipulated by scientists using, for example, high magnetic fields.
Crystals are easy to make and observe with the naked eye, a magnifying glass, or a microscope.
Each of those tools reveals a different level of complexity in the crystal. This activity introduces students to crystal structures and a new way of looking at things. If your students are proficient at using microscopes, then they can now investigate some special properties of crystals. Crystals that are anisotropic are also optically anisotropic. An anisotropic crystal whose lattice is the same along two directions but different along the third, is double refractive or birefringent.