Catapleiite and Feldspar from Mont St. Hiliare
Contributed by: Michael Crawford
Date: Jun 23rd, 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: 5 x 5.5 cm
Description:
This specimen contains catapleiite (Na2Zr(Si3O9) · 2H2O) and feldspar from Poudrette Quarry, Mont St. Hilaire, Quebec, Canada. Catapleiite fluoresces green due to uranyl impurities, with fluorescence mainly from the crystal fringes.
The midwave emission spectrum shows two sharp peaks at 503 nm and 523 nm due to the uranyl activation. There is a feldspar crystal next to the mass of catapleiite crystals. The feldspar fluoresces red under shortwave illumination. Measurements of shortwave spectra of the feldspar exhibited variability in the peak position of the emission. The peak varied from 688 nm to 721 nm. This variation is due to the change in composition from a potassium rich feldspar (microcline) with a peak at 688 nm to a sodium rich feldspar (albite) with a peak at 721 nm).
Near infrared and color infrared images of shortwave fluorescence reveal compositional variations in the feldspar. The color infrared image is made by assigning the near infrared image to red, the red visible image to green, and the green visible image to blue. Catapleiite appears blue in the image. Albite rich feldspar is orange to red. Microcline rich feldspar is a greenish hue and yellow hues are intermediate between albite and microcline. The color infrared image shows the feldspar crystal has a rim of albite.
Summary of luminescence responses:
Catapleiite (Mindat) (RRUFF)
- Fluorescence under Midwave (305nm LED) UV light: Green
- Fluorescence under Shortwave (255nm LED) UV light: Green
- Fluorescence under Shortwave (255nm LED) UV light: Red
- Fluorescence under Shortwave (255nm LED) UV light: Red