Introduction

The following pages contain descriptions and illustrations of some cubic and hexagonal crystal lattices and their unit cells.

A lattice is a regular array of lattice points in three dimensions, and a crystallographic unit cell is a parallelapiped formed by connecting eight lattice points.

A cubic unit cell is characterized by six square faces and three equal non-coplanar edges:
a = b = c. The volume of a cubic unit cell is a^.b^.c or

V = a³ Nearest neighbor coordination spheres are easily characterized in cubic lattices.

A hexagonal unit cell is characterized by four rectangular faces (with edges a & c and b & c) and two parallelograms with equal sides (a = b) and interior angles of 60^o and 120^o. The volume of a hexagonal unit cell is a^.b^.c^.sin(120^o) or

Most of the illustrations in the following pages are crossed-stereo pairs. To view them, cross your eyes and focus.

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