Hemimorphite - Ojuela Mine, Mapimi, Mexico

Contributed by: Chris Clemens
minID: E9K-YVL
Date: May 1st, 2026
Locality: Ojuela Mine, Mapimí, Mapimí Municipality, Durango, Mexico (See on Mindat)
Size: 8 x 5.1 x 8.4 cm
Weight: 235 g

Description:
Light-colored crystals of hemimorphite on a red/brown limonitic gossan matrix, collected from the Ojuela Mine, Mapimí, Durango, Mexico. The hemimorphite fluoresces green under all UV wavelengths, brightest under midwave UV.

The green fluorescence is no doubt caused by uranyl-activation- the presence of trace amounts of uranium in the hemimorphite, but this specimen does not emit detectable levels of radioactivity.

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

Fluorescence under midwave UV light.

Normal light.

Fluorescence under shortwave UV light. Closeup FOV = 32mm

Normal light. Closeup FOV = 32mm

Summary of luminescence responses:

Hemimorphite (Mindat) (RRUFF)

• Fluorescence under Midwave (305nm Lamp/Mercury) UV light: Green