Fluorescent Mineral Database

A new secret project! Trying to create a nice Fluorescent Mineral Database (FMDB), which would be searchable by mineral, locality, and luminescence properties. Also making it easy for people to contribute with their own specimens!

Brightly Fluorescent Hyalite Opal from the Erongo Mountains, Namibia

Contributed by: Chris Clemens
minID: C6F-5T8
Date: Apr 16th, 2026
Locality: Erongo Mountains, Erongo Region, Namibia (See on Mindat)
Size: 9.5 x 3.2 x 14.3 cm
Weight: 360 g

Description:
This brilliantly fluorescent specimen from the Erongo Mountains of Namibia features colorless to greenish-yellow, transparent, glassy bubbles of hyalite opal (Opal-AN) covering a granite matrix. The hyalite opal shows a bright green, fluorescent response under all UV wavelengths, and also exhibits yellow/green daylight fluorescence under sunlight. The green, fluorescent response seen in this material is due to trace amounts of uranium included in the opal silica. Due to the uranium content, this specimen is moderately radioactive and was measured at 800 cpm at 1 cm.

Originally posted by Chris Clemens on Nature's Rainbows in 2022.

Fluorescence under shortwave UV light.
Fluorescence under shortwave UV light.
Fluorescence under longwave UV light.
Fluorescence under longwave UV light.
Normal light.
Normal light.

Summary of luminescence responses:

Opal-AN (Mindat) (RRUFF)

  • Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Green
  • Fluorescence under Longwave (365nm LED) UV light: Green

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