Fluorescent Calcite Vein in Wheeler Shale, Delta, Utah
Contributed by: Chris Clemens
Date: Apr 26th, 2026
Locality: Delta, Millard County, Utah, USA (See on Mindat)
Size: 6.2 x 0.7 x 10 cm
Description:
This is a simple, but interesting fluorescent specimen that dates back to the age of the trilobites. A vein of light-colored calcite fills a fracture in a matrix of grey Wheeler Shale. Under shortwave UV, the calcite fluoresces bright red/orange, contrasting against the non-fluorescent shale. The calcite vein is approximately 1.5 mm wide. This specimen was collected from the world-famous trilobite beds in the House Range, near Delta, Millard County, Utah. The Wheeler Shale was deposited during the Cambrian period approximately 500 million years ago and is known for producing a great variety of finely-preserved fossils of marine invertebrates including over 500 species of trilobites.
Originally posted by Chris Clemens on Nature's Rainbows in 2017
Summary of luminescence responses:
Calcite (Mindat) (RRUFF)
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Red