The symbol above shows a sixfold axis perpendicular to the plane of the screen,
i.e parallel to Z.
A sixfold axis is equivalent to an anticlockwise rotation of 60°
about a line.
A sixfold rotation about the c-axis, i.e. about
the line 0,0,z, will have
the corresponding symmetry operator x-y,x,z.
This axis has the written symbol "6".
