Selenite - Baja California, Mexico

Contributed by: Chris Clemens
Date: Apr 28th, 2026
Locality: Guerrero Negro, Mulegé Municipality, Baja California Sur, Mexico (See on Mindat)
Size: 43 x 28 x 64 mm
Weight: 40 g

Description:
This is a cluster of white, bladed, intergrown crystals of selenite from an interesting location in Baja California, Mexico. Located at Scammon's Lagoon, near the town of Guerrero Negro, Baja California Sur, Mexico, is a large facility that produces salt by the evaporation of sea water. One of the products of this process are these beautiful rosette-like clusters of selenite crystals. In addition to providing aesthetic visible light display specimens, these selenite crystals are also fluorescent and phosphorescent under UV. Under all UV wavelengths the selenite blades show a soft, blue/white, fluorescent response, brightest under longwave. After shortwave UV, blue phosphorescence is seen, and a dim green phosphorescent response occurs following exposure to longwave UV.

Originally posted by Chris Clemens on Nature's Rainbows in 2017.

Fluorescence under shortwave UV light.

Afterglow after exposure to shortwave UV light.

Fluorescence under longwave UV light.

Afterglow after exposure to longwave UV light.

Normal light.

Summary of luminescence responses:

Gypsum var. Selenite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: White
• Afterglow after exposure to Longwave (365nm LED) UV light: Green
• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: White
• Afterglow after exposure to Shortwave (254nm Lamp/Mercury) UV light: Blue