Aragonite and Calcite - Promontory Mts., Utah

Contributed by: Mark Cole
Date: Mar 24th, 2026
Locality: Promontory Mountains, Box Elder County, Utah, USA (See on Mindat)

Description:
Originally posted by Mark Cole on Nature's Rainbows in 2015.

Fluorescence under shortwave UV light.

Fluorescence under longwave UV light.

Afterglow after exposure to shortwave UV light.

Normal light.

Summary of luminescence responses:

Aragonite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: White
• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: White
• Afterglow after exposure to Longwave (365nm LED) UV light: Blue

• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Red