Multi-wavelength Tenebrescent Hackmanite - Sudbury District, Ontario, Canada

Contributed by: FMS Admin
minID: N0L-3P6
Date: May 17th, 2026
Locality: Sudbury District, Ontario, Canada (See on Mindat)
Size: 6 x 3.4 x 11.7 cm

Description:
Nice cabinet-sized specimen of sodalite var. hackmanite, from a recent find in the District of Sudbury, in Ontario, Canada. It is associated with feldspar (dull red SW), and some blueish-white fluorescing calcite. Small dots of a bright yellow fluorescing unknown (likely zircon, possibly apatite) show up under MW and SW; and some red unknown (possible calcite) shows up under MW. The hackmanite is nicely tenebrescent upon exposure to all wavelengths (darkest upon SW and MW exposure).

Originally posted by Frédéric Messier Leroux on Nature's Rainbows in 2021.

Fluorescence under longwave UV light.

Tenebrescence after exposure to longwave UV light.

Fluorescence under shortwave UV light.

Tenebrescence after exposure to shortwave UV light.

Fluorescence under midwave UV light.

Normal light.

Summary of luminescence responses:

Hackmanite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Orange
• Fluorescence under Midwave (305nm LED) UV light: Red
• Fluorescence under Shortwave (255nm LED) UV light: Red
• Tenebrescence after exposure to Longwave (365nm LED) UV light: Purple
• Tenebrescence after exposure to Shortwave (255nm LED) UV light: Purple