Uploaded March 2025 | Updated September 2026, 2 weeks ago

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The rock formations in caves are chemistry fossils — that glow.

These rocks are made of calcite, a form of calcium carbonate. Impurities trapped in calcite cause the mineral to fluoresce different colors under UV light, ranging from pink and purple to blue, green and yellow. Scientists from the University of Northern Iowa are learning how to match this colored glow to trace metals and organic compounds, providing information on the cave’s history and development.

“Developing a cave science spectral database for fluorescence inventory”
Presented at ACS Spring 2025 on March 25, 2025
Presenter: Anna Van Der Weide
Principal investigator: Joshua Sebree, Ph.D.

To read an ACS press release about this research, go to: acs.org/pressroom/presspacs/2025/march/fluorescent-caves-could-explain-how-life-persists-in-extraterrestrial-environments.html

Video credits:
Written and produced by Anne Hylden
Edited by Mónica Pinzón
Narrated by Allison Tau
Series produced by Vangie Koonce and Andrew Sobey
Executive produced by Matthew Radcliff

Research videos and photos from Joshua Sebree, Ph.D., and the University of Northern Iowa Department of Communication and Media

Additional video: Getty Images
Sound effects: Triple Scoop Music
Music: “Beyond Space (Instrumental)” by Roger Gabalda from Triple Scoop Music

See @astrobiologyunderground for more cosmic spelunking videos!

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