We Can Figure This Out.org
Virtual Lab: Crystal Facets and Miller Indicies
University of Virginia
© 2003-Present, John C. Bean
This presentation explains how scientists label the facets of crystals using "Miller indices."

The presentation employs an interactive 3D model that you can rotate, move or magnify. This model is presented using secure "Three.js" JavaScript (replacing earlier use of the "Flash" plugin). But this model can take a while to load into your browser. PLEASE BE PATIENT.

Crystals are known for their "symmetries." Meaning that they have axes around which they can be rotated to realign facets with one another.

The simplest symmetry is "cubic symmetry." Cubic crystals have three perpendicular axes (generally labeled x, y, z). Their facets are realigned by rotations of 90, 180, or 270 degrees around these axes. Diamond and most semiconductor crystals have cubic symmetry (e.g., silicon and gallium arsenide).

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