Multi-color Fluorescent Specimen from the Rampgill Mine, Cumbria, England
Contributed by: Michael Crawford
Date: Jul 21st, 2025
Locality: Rampgill Mine, Nenthead, Alston Moor, Eden, Cumbria, England, UK (See on Mindat)
Size: 6.5 x 10 cm
Description:
A multi-color fluorescent specimen from the Rampgill Mine, Nenthead, Cumbria, England. The specimen has witherite (BaCO3) that is white under all wavelengths of UV light, fluorite (CaF2) that is blue under all wavelengths of UV light, and barytocalcite (BaCa(CO3)2) that is pink under midwave and shortwave UV light. There are also some small patches of red fluorescent calcite in the shortwave image. The witherite is also phosphorescent after exposure to all wavelengths of UV light.
The longwave and shortwave emission spectra of fluorite have a peak at 422 nm. This peak is activated by europium replacing calcium in the fluorite structure. There are also some small peaks in the ultraviolet region that is activated by cerium that also replaces calcium.
The witherite spectra have much broader peaks compared to fluorite. The longwave peaks at 447 nm and the shortwave peaks at 433 nm. Fluomin.org describes europium as the activator for the fluorescence. The barytocalcite has a complex shortwave spectrum. The brightest peak is in the ultraviolet region with a maximum at 346 nm. This may be activated by cerium. There is a second broad peak with a maximum at 449 nm. The activation of this peak is unknown. There is also a subtle peak around 600 nm to 620 nm that gives the barytocalcite its pinkish hue. This peak may be activated by manganese.
Summary of luminescence responses:
Witherite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: White
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: White
- Fluorescence under Shortwave (255nm LED) UV light: White
- Afterglow after exposure to Shortwave (255nm LED) UV light: White
- Fluorescence under Midwave (305nm LED) UV light: Pink
- Fluorescence under Shortwave (255nm LED) UV light: Pink
- Fluorescence under Longwave (365nm LED) UV light: Blue
- Fluorescence under Midwave (305nm LED) UV light: Blue
- Fluorescence under Shortwave (255nm LED) UV light: Blue