Above: A hexagonal (six-sided) snow crystal, classified as a stellar dendrite. This crystal was photographed with an Olympus TG-6 camera after it landed on the sleeve of the authors fleece jacket.

An illustration of individual atoms of three different noble gases--argon, krypton, and xenon--getting trapped in a 2-D array of nanosized "cages." These porous frameworks have a hexagonal prism shape ...

A prism has a constant cross-section throughout its length. When the cross-section is a triangle, the prism is called a triangular prism. When the cross-section is a hexagon, the prism is called a ...