Metallic Crystals - The Structures of Pure Metals
Hexagonal Closest-Packed Structure
The two models on this page show that the layer of yellow spheres in the foreground and the underlying layer of red spheres are superposable. The red and yellow spheres occupy directly opposing sides of the same holes in the layer of gray spheres. In the space-filling model it is possible to spot the color of the lower layer through the unoccupied holes.