Like Hot Rocks? Autunite from the Daybreak Mine, Spokane, Washington

Contributed by: Mark Cole
Date: Apr 6th, 2026
Locality: Daybreak Mine, Mount Kit Carson, Spokane County, Washington, USA (See on Mindat)
Size: 1 x 0.5 x 2 inches
Weight: 0.7 oz

Description:
This is about as hot as I want to get - check the meter: 3,600CPM. Autunite is equally fluorescent under all wavelengths (shortwave shown) and is very bright. Great little specimen from a classic locality.

Shortwave fluorescent picture was taken at ISO-100, f/8 for 1/5 second.

Originally posted by Mark Cole on Nature's Rainbows in 2016.

Fluorescence under shortwave UV light.

Normal light.

Autunite specimen with Geiger counter showing the autunite's radioactivity of 3600 CPM

Summary of luminescence responses:

Autunite (Mindat) (RRUFF)

• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Green
• Fluorescence under Midwave (305nm Lamp/Mercury) UV light: Green
• Fluorescence under Longwave (365nm LED) UV light: Green