Why do some rocks glow under UV light?
Show answer & explanation
Answer: Fluorescent minerals absorb UV
Stored sunlight releasing — Wrong. Rocks don't store sunlight like batteries. Fluorescence happens instantly when UV light hits certain minerals, exciting electrons that emit visible light.
Fluorescent minerals absorb UV ✓ — Correct! Minerals like fluorite, calcite, and willemite contain atoms that absorb high-energy UV light, exciting electrons to higher energy states. When electrons drop back down, they release lower-energy visible light—creating glowing colors! It's called fluorescence (named after fluorite!). No glow without UV light.
Heat from Earth's core — Wrong. Fluorescence is from UV light interaction with minerals, not geothermal heat. Heat doesn't make rocks glow visibly.
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