Multi-Colored Wickenburgite, Willemite and Fluorite, from the Potter-Cramer Mine, Maricopa County, Arizona

Contributed by: Chris Clemens
Date: Apr 24th, 2026
Locality: Potter-Cramer Mine, Vulture Mining District, Maricopa County, Arizona, USA (See on Mindat)
Size: 47 x 37 x 51 mm
Weight: 70 g

Description:
From the desert of southern Arizona, this is a very ordinary and nondescript looking rock in daylight, as is the case with many fluorescent mineral specimens. It contains wickenburgite, willemite and fluorite, and was collected from the Potter-Cramer Mine, near Wickenburg. Under the light of the UV lamp, however, this rock comes to life, showing a beautiful multi-colored fluorescent response. Under shortwave UV the wickenburgite glows magenta/red, the willemite pale green/blue, and the fluorite deep blue. The willemite is also brightly phosphorescent for an extended period of time. Under longwave UV, the fluorite shows a classic deep blue/purple response.

The Potter-Cramer Mine is located in the Vulture Mountains, south of Wickenburg, Arizona. It is also the type locality for the mineral wickenburgite, meaning that the mineral was first discovered there. The mine has been a producer of zinc, lead, copper, gold, vanadium, and wickenburgite specimens.

Originally posted by Chris Clemens on Nature's Rainbows in 2016.