Hackmanite, Feldspar, Astrophyllite, etc. - Mont Saint-Hilaire, Quebec, Canada
Contributed by: FMS Admin
Date: May 16th, 2026
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: 12.9 x 8.6 x 14.5 cm
Description:
Shown in the images below is a nice combination piece consisting mostly of brightly fluorescing hackmanite, with some SW fluorescing feldspar (not really impressive - typical dull red SW response of feldspar), plus some unidentified brown mineral with a green SW response. The tenebrescence of this hackmanite specimen is quite mediocre, compared to average hackmanite specimens from Mont Saint-Hilaire; however, some non-fluorescent radiating astrophyllite gives some extra beauty to the specimen in visible light. The shortwave fluorescence of this specimen is a bit brighter than usual; Mont Saint-Hilaire hackmanite is usually quite dim under SW, even before the tenebrescence sets in. It is brighter than usual SW response is most likely due to the fact that most of this specimen is not tenebrescent.
Specimen collected in 2018.
Originally posted by Frédéric Messier Leroux on Nature's Rainbows in 2021.
Summary of luminescence responses:
Hackmanite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Orange
- Fluorescence under Midwave (305nm LED) UV light: Orange
- Fluorescence under Shortwave (255nm LED) UV light: Red
- Tenebrescence after exposure to Shortwave (255nm LED) UV light: Purple