Yttrofluorite and Albite from Norway
Contributed by: Michael Crawford
Date: Jul 14th, 2025
Locality: Innhavet, Hamarøy, Nordland, Norway (See on Mindat)
Size: 7.5 x 10 cm
Description:
A yttrofluorite specimen from Innhavet, Drag, Nordland, Norway. Yttrofluorite ((Ca1-xYx)F2+x) is a variety of fluorite containing an appreciable amount of trivalent yttrium (Y3+) taking the place of divalent calcium (Ca2+) cations in the fluorite structure. The specimen also contains fluorescent albite and non-fluorescence allanite-(Ce). The allanite-(Ce) forms black reaction rims around the grains of yttrofluorite.
The emission spectra have numerous peaks indicative of rare earth element (REE) activation of the fluorescence. The shortwave emission has a very bright peak in the ultraviolet with a maximum at 310 nm. This ultraviolet fluorescence is considerably brighter than the visible fluorescence of the yttrofluorite. The fluorescence is activated by yttrium (Y3+) replacing calcium. The other peaks in the visible are activated by other REE’s. Dysprosium (Dy3+), Terbium (Tb3+), and Erbium (Er3+) are possible REE activators.
The color of the yttrofluorite fluorescence changes with different wavelengths of illumination. It is green under longwave UV illumination and white under midwave and shortwave illumination. There is a prominent peak composed of two sharp peaks with maxima at 539 nm and 545 nm. This doublet is responsible for the green hue in the longwave fluorescence, and it is activated by terbium (Tb3+) and/or erbium (Er3+). The peaks at 477 nm and 570 nm are activated by dysprosium and are the main contributors to the cream-colored fluorescence under shortwave light.
The specimen also contains albite that fluoresces red under shortwave illumination. The albite emission spectrum peaks in the near infrared at 724 nm. There is also a peak in the ultraviolet at 311 nm that may be caused by yttrium in the albite structure.
Images of the ultraviolet and near infrared fluorescence confirm the information in the emission spectra. The light blue areas in the false color image of ultraviolet fluorescence are from the yttrofluorite 310 nm emission peak. The ultraviolet fluorescence of the albite observed in the emission spectrum is not evident in the false color image because the yttrofluorite ultraviolet fluorescence is significantly brighter.
The red color in the color infrared image is from the albite emission peak with the maximum at 724 nm.
Summary of luminescence responses:
Yttrofluorite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Green
- Fluorescence under Midwave (305nm LED) UV light: White
- Fluorescence under Shortwave (255nm LED) UV light: White
- Fluorescence under Shortwave (255nm LED) UV light: Red