Natrolite from Mont St. Hiliare, Quebec, Canada
Contributed by: Michael Crawford
Date: Jun 27th, 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 12.5 cm
Description:
A specimen of natrolite (Na2Al2Si3O10 · 2H2O), albite, brown siderite, and a blue-fluorescent unknown mineral from the Poudrette Quarry, Mont St. Hiliare, Quebec, Canada (MSH). The natrolite occurs as small, clear orthorhombic crystals. The intensity of the fluorescence varies within the crystals (see image enlargement).
The natrolite emission spectrum shows the green fluorescence is uranyl ion activated. The emission spectrum of the red fluorescent mineral peaks at 719 nm indicating it is albite activated by ferric iron. I have another natrolite specimen from MSH with a red fluorescent mineral. Its spectrum identified it as microcline. So, it is possible for both types of feldspar to be associated with natrolite at MSH.
The unknown mineral with bluish-white fluorescence has a broad shortwave emission with a maximum at 458 nm. There are no obvious crystal shapes for the unknown mineral. It is likely a zeolite like natrolite. The zeolites analcime and gonnardite are commonly found in association with natrolite at MSH. They are the most likely candidates.
Summary of luminescence responses:
Natrolite (Mindat) (RRUFF)
- Fluorescence under Shortwave (255nm LED) UV light: Green
- Fluorescence under Shortwave (255nm LED) UV light: Red