Zon"al (?), a. [L. zonalis.]
Of or pertaining to a zone; having the form of a zone or zones.
Zonal equation Crystallog., the mathematical relation which belongs to all the planes of a zone, and expresses their common position with reference to the axes. -- Zonal structure Crystallog., a structure characterized by the arrangements of color, inclusions, etc., of a crystal in parallel or concentric layers, which usually follow the outline of the crystal, and mark the changes that have taken place during its growth. -- Zonal symmetry. Biol. See the Note under Symmetry.
© Webster 1913.