Green Fluorescent Emerald from Muzo, Colombia
Contributed by: Michael Crawford
Date: Aug 29th, 2025
Locality: Muzo Mine, Muzo Municipality, Western Boyacá Province, Boyacá Department, Colombia (See on Mindat)
Size: 2.5 x 10 cm
Description:
Green crystals of emerald from Muzo, Colombia. Emerald is a variety of beryl (Be3Al2(Si6O18)). Trace amounts of chromium, vanadium, and iron are responsible for the green color in daylight. Chromium (Cr3+) and ferric iron (Fe3+) can also cause it to fluoresce under longwave UV light. The emerald is non-fluorescence under midwave and shortwave light. Many emeralds do not fluoresce. This emerald is unusual in that it fluoresces blue green instead of the more typical red.
The longwave and 405 nm laser emission spectra of this emerald have a sharp peak at 685 nm caused by chromium. The sharp peak occurs on the shoulder of a much broader peak with a maximum in the near infrared at 732 nm. These two features in the spectra of green, fluorescent emerald are also found in emission spectra of red fluorescent emeralds from Muzo. Two types of red fluorescent emeralds are found at Muzo. One type has a peak fluorescence at 714 nm and the other peaks at 731 nm. The broad peaks are activated by chromium and possibly ferric iron.
The difference between red and green, fluorescent emerald is the broad peak at 492 nm. This is the green fluorescence emitted by the emerald. This green fluorescence may be activated by manganese or rare earths. More study is needed to understand this green fluorescence.
The last two images show the infrared fluorescence of the emerald.
Summary of luminescence responses:
Beryl var. Emerald (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Green