Symmetry - Exact proportion from an intermediate center horizontal line, vertical line, or central point. If an object has symmetry, than it can be rotated or flipped and appear the the exact same way it was before the rotate or flip. The axes (x axis and y axis) are imaginary lines drawn through the center of the shape; the x axis going in a horizontal direction, the y axis going in a vertical direction. There are three types of symmetry:

Symmetry about a center point (figure 1) - Will retain the same shape even if flipped over both the x and y axes. Can be rotated 90° and will still retain the same shape.

Symmetry about the x axis (figure 2) - Will retain the same shape if flipped over the the x axis.

Symmetry about the y axis (figure 3) - Will retain the same shape if flipped over the the y axis.

See also Axis of symmetry and Crystals in mineral properties for more information.