Rocks That Glow in the Dark

Willemite-Calcite fluorescing, specimen from Franklin Mining District, Sussex County, NJ (photo from Wikimedia Commons)

24 March 2022

Because we humans can’t see ultraviolet light we miss the fact that some rocks glow in the dark after exposure to sunlight.

The glowing orange and green rock at top is a composite of willemite (normally brown glowing green) and calcite (normally white glowing orange). On display under normal light it is boring by comparison.

Willemite-Calcite in normal light, specimen from Franklin Mining District, Sussex County, NJ (photo from Wikimedia Commons)

Other rocks can glow, too. Did you know that about 30% of diamonds glow under ultraviolet light? 99% of them glow blue but a few glow white, yellow, green, or red as shown below. See the explanation at Diamond Pro.

Fluorescing diamonds from Russia (photo from Wikimedia Commons)
Fluorescing diamonds from Zaire (photo from Wikimedia Commons)

And here’s a rock called blueschist (benitoite-neptunite-joaquinite-natrolite) that is housed at the Carnegie Museum of Natural History. In black light it would stop me in my tracks.

Blueschist with fluorescing benitoite-neptunite-joaquinite-natrolite vein, Carnegie Museum of Natural History (photo from Wikimedia Commons)

Under normal display it is merely interesting.

Blueschist with benitoite-neptunite-joaquinite-natrolite under normal light, Carnegie Museum of Natural History (photo from Wikimedia Commons)

Birds can see ultraviolet light so they see these rocks in all their beauty. Alas we cannot without black light.

On Throw Back Thursday learn more about glowing rocks at:

(photos from Wikimedia Commons; click on the captions to see the originals)

One thought on “Rocks That Glow in the Dark

  1. We spent a lot of mornings at the Carnegie museum when my kids were small. Every visit had to include a sit down in the fluorescent minerals room. I think I remember all of the script to the narrative, and my youngest child is 31 years old. Thanks for dredging up that happy memory!

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