Calcite Cleavage Rhomb, Challenger Cave, Nuevo Leon, Mexico
Contributed by: Chris Clemens
Date: Apr 25th, 2026
Locality: Challenger Cave System, Monterrey Municipality, Nuevo León, Mexico (See on Mindat)
Size: 34.5 x 19.2 x 46.3 mm
Weight: 58 g
Description:
A brightly fluorescent and phosphorescent calcite cleavage rhomb from Challenger Cave, Nuevo Leon, Mexico. This specimen shows classic Terlingua-type fluorescence under UV- a blue response with bright and lasting phosphorescence under shortwave, and a bright pink response with brief, dim phosphorescence under longwave. This calcite also fluoresces bright yellow/white with phosphorescence under midwave UV. These specimens from Nuevo Leon, Mexico, are fairly common and look like ice cubes under visible light but show an almost magical fluorescent response under all UV wavelengths.
Challenger cave is a series of 7 caverns that has historically been a prolific source for these optically clear and brightly fluorescent calcite cleavage rhombs.
Originally posted by Chris Clemens on Nature's Rainbows in 2016.
Summary of luminescence responses:
Calcite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Pink
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: White
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Violet
- Afterglow after exposure to Shortwave (254nm Lamp/Mercury) UV light: Blue
- Afterglow after exposure to Midwave (305nm Lamp/Mercury) UV light: Blue
- Afterglow after exposure to Longwave (365nm LED) UV light: Green