Unique Multi-Wave Calcite - Cave-In-Rock, Illinois

Contributed by: Chris Clemens
Date: May 1st, 2026
Locality: Hastie's Quarry, Spar Mountain (Iron Mountain), Cave-In-Rock Mining Sub-District, Hardin County, Illinois, USA (See on Mindat)
Size: 59.5 x 54 x 70 mm
Weight: 232 g

Description:

This calcite was mined by the Griffith family in 2017 from their private commercial specimen mining operation located in Hastie's Quarry in the Spar Mountain area near Cave-In-Rock, Illinois. Under longwave UV the calcite shows a beautiful rich orange, fluorescent response, and a similar, but dimmer response is seen under shortwave UV. This piece really comes to life under midwave UV, showing bright pink/magenta fluorescence.

There are also clusters of small, cubic, dark purple colored fluorite crystals on this specimen, but they are not fluorescent.

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

Fluorescence under longwave UV light.

Fluorescence under midwave UV light.

Fluorescence under shortwave UV light.

Normal light.

Summary of luminescence responses:

Calcite (Mindat) (RRUFF)

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