Öйú365betÖÐÎĹÙÍø

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.

Read an ACS press release about this research: Fluorescent caves could explain how life persists in extraterrestrial environments.

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

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
Music: “Beyond Space (Instrumental)� by Roger Gabalda from Triple Scoop Music

Transcript

In normal light, this cave is beautiful. But in ultraviolet light, it tells a story.

The calcite in these formations fluoresces under black light. That fluorescence changes color depending on which impurities are trapped in the rock. And that gives clues about organic compounds and trace metals that have leached in from the surface, potentially showing how life above ground affects life hundreds of feet below.

Scientists from the University of Northern Iowa explore caves and map the colors emitted by the rocks in different locations. The group is building a library of calcite fluorescence to share with other scientists who want to study caves without destroying million-year-old formations. They also hope their work sheds light on the chemistry of other extreme environments, such as the icy moons of Saturn.

This research is being presented at ACS Spring 2025, a meeting of the American Chemical Öйú365betÖÐÎĹÙÍø.