Microcline and Smokey Quartz - Lolo Pass, Montana

Contributed by: FMS Admin
Date: May 7th, 2026
Locality: Lolo Pass, Missoula County, Montana, USA (See on Mindat)
Size: 2.5 inches

Description:
Granted, this is not the brightest piece around, but it is very intriguing. The microcline under longwave fluoresces a decent whitish blue. Under midwave, it fluoresces soft lavender. Then under shortwave, it glows a deep red. Checked it for reflection, but it's mostly glow. The quartz glows not a bit, sadly. Disclaimer, I struggled getting the color correct. While they are not perfect, they are close.

Originally posted by Fire Viper on Nature's Rainbows in 2018.

Fluorescence under longwave UV light.

Fluorescence under midwave UV light.

Fluorescence under shortwave UV light.

Normal light.

Summary of luminescence responses:

Microcline (Mindat) (RRUFF)

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