This is an image of two crystal forms; the Japanese Tsuzumi is an
unusual variation. The capped column formation is a good example of growth
along both the A and C axes. The three A-axes are seperated at 120 degrees and
have 3-fold hexagonal symmetry. The C-axis grows at 90 degrees to the A-axes and
is the weaker of the two axis types, particularly perpendicular to the surface
plane.
