Elpidite and Albite from Mont St. Hiliare
Contributed by: Michael Crawford
Date: Jun 22nd, 2025
Locality: Poudrette quarry (De-Mix quarry; Demix quarry; Uni-Mix quarry; Carrière Mont Saint-Hilaire; MSH), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada (See on Mindat)
Size: 6 x 7.5 cm
Description:
This is a specimen of elpidite (Na2ZrSi6O15·3H2O) and albite Na(AlSi3O8) from the Poudrette Quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada. The elpidite fluoresces green under midwave and shortwave UV illumination. The shortwave emission spectrum has a single peak with a maximum at 525 nm like the willemite emission spectrum. However, the elpidite spectrum is much wider than the willemite emission spectrum. Fluomin.org attributes the green fluorescence to uranyl activation, but the elpidite spectrum for this specimen lacks the multiple peaks seen in emission spectra of uranyl activated minerals. The elpidite in this specimen is slightly radioactive (50 cpm) indicating the presence of uranium. There may be some constraint that limits the vibration of the uranyl ion or makes the peaks close to one another. The elpidite activator in this specimen may be uranyl ions or possibly manganese.
Summary of luminescence responses:
Elpidite
- Fluorescence under Midwave (305nm LED) UV light: Green
- Fluorescence under Shortwave (255nm LED) UV light: Green