Willemite, Calcite and Fluorite from the Southwest: Hogan Claim, Arizona

Contributed by: Chris Clemens
Date: Apr 29th, 2026
Locality: Great Southern Mine, Monarch Wash area, Black Rock Mining District, Yavapai County, Arizona, USA (See on Mindat)
Size: 7 x 5.4 x 8.1 cm
Weight: 352 g

Description:
Under normal daylight, this is a rather nondescript looking rock, but when viewed under UV it explodes with color in a spectacular multi-wavelength fluorescent response. This specimen contains willemite, calcite and minor fluorite, and was collected from the Hogan Claim (Hogan Mine), Wickenburg area, Yavapai County, Arizona, in 2002. Under shortwave UV the calcite fluoresces red, the willemite green/white, and the fluorite glows deep blue. The willemite also shows lasting phosphorescence after the shortwave lamp is shut off. Under midwave UV the calcite dominates with red fluorescence. Longwave UV brings out the blue, fluorescent fluorite. This specimen is most spectacular when viewed under fullwave UV (shortwave + midwave + longwave).

The Hogan Claim is a former fluorspar (fluorite), silver, gold, lead and molybdenum mine, and is located near Red Picacho Peak in the Wickenburg area. It is also located on the same mountain as the Purple Passion Mine, another prolific source of fluorescent mineral specimens.

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