The minerals are lit by ultraviolet light, which coverts a small amount of light into heat, and return the rest as visible light causing them to glow.

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Photo credit: © World History Archive / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: archival, archive, florescent, glow, glowing, heat, historical, history, invisible, light, minerals, natural, nature, ultraviolet, uv