Fluorescent Calcite and Agate, in a Geode from the Gaspé Peninsula, Quebec, Canada
Contributed by: FMS Admin
minID: AL1-WR2
Date: May 13th, 2026
Locality: Mont Lyall Agate Mine, La Haute-Gaspésie RCM, Gaspésie-Îles-de-la-Madeleine, Québec, Canada (See on Mindat)
Size: 10.5 x 7.4 x 12.2 cm
Description:
While it is far from being my most impressive and brightest fluorescent mineral specimen, I thought this one was worth posting here since it comes from a locality that is never, or at least very rarely, heard of as a fluorescent mineral producing locale. It comes from the Mont Lyall agate mine in the highlands of the Gaspé peninsula in Quebec, Canada, in the Shickshock Mountains (part of the Appalachians). Nice, but usually heavily fractured agates and geodes are collected in this "collect-for-fee" mine, which consists of a series of small trenches dug in clay resulting from the weathering of rhyolite, on the flank of an old volcano. Sometimes, the nodules/"thundereggs" have a hollow center coated with clear or smoky quartz crystals, and more rarely, pale amethyst. In some cases, the cavity was later filled with calcite and/or iron oxides (limonite/goethite).
The agate bands on this specimen fluoresce a very weak green under shortwave, but the calcite fluoresces very bright red. Based on my visual observations, I would say it fluoresces about 75-80% as bright as the brightest fluorescent calcites of the Franklin district in New-Jersey. Had this specimen not included this bright fluorescing calcite, I would have disregarded it as a decent fluorescent specimen since the response of the agate is very weak, but the combination of both the calcite center fill and the agate make it just good enough for a display.
Originally posted by Frédéric Messier Leroux on Nature's Rainbows in 2022.
Summary of luminescence responses:
Calcite (Mindat) (RRUFF)
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Red
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Green