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Smithsonian National Museum of Natural History

Albite (var. moonstone)

Photograph of a moonstone with blue iridescence (NMNH G3171) from the National Gem Collection
Photo by Chip Clark. Click to zoom.
Catalog Number NMNH G3171-00
Locality Rutherford Mine, Virginia, United States
Weight 58 ct

From the exhibit

Look at these minerals from one direction, then another, to catch the play of light.

Labradorites, moonstones, and sunstones belong to the feldspar family, which makes up over half of the Earth’s crust. Occasionally, this common material forms crystals that shimmer like a rainbow on a soap bubble. This iridescence occurs when closely spaced layers in a crystal diffract light, separating it into its component colors.

Look for:

  • sunstones flashing golden orange (from flecks of goethite or copper).
  • a labradorite crystal with concentric bands of iridescent color.
  • moonstones, known for bluish-white iridescence.


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