Golden Yellow Fluorescent Zircons from Saint Peters Dome, El Paso County, Colorado
Contributed by: Chris Clemens
minID: NNN-E0G
Date: Apr 20th, 2026
Locality: St Peters Dome, Cheyenne Mining District (St. Peters Dome Mining District), El Paso County, Colorado, USA (See on Mindat)
Size: 45 x 25 x 54 mm
Weight: 58 g
Description:
This is a lovely fluorescent specimen featuring numerous red/purple colored zircon crystals in a grey/white translucent quartz matrix with minor blue/grey fluorite in a non-fluorescent quartz matrix. There is also an unidentified greenish mineral present, possibly epidote. Collected from the Eureka Tunnel, St. Peters Dome, El Paso County, Colorado.
Midwave UV (305nm) light provides the best overall fluorescent response inducing bright golden yellow fluorescence from the zircon crystals and blue from the fluorite. The zircon crystals show their brightest response under shortwave UV (254 nm), but the fluorite only fluoresces a dim, pale blue. The zircons fluoresce a moderate orange color under longwave UV (365 nm), while the fluorite shows its brightest blue response.
Located in the Pikes Peak area of Colorado, St. Peter's Dome has been the site of numerous fluorspar and other mining operations dating back to the early 1900s. St. Peter\'s Dome is a a granite-topped peak on the Pikes Peak massif in the Pike National Forest.
Originally posted by Chris Clemens on Nature's Rainbows in 2019.
Summary of luminescence responses:
Zircon (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Yellow
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: Yellow
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Yellow
- Fluorescence under Longwave (365nm LED) UV light: Blue
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: Blue