Aegirine pseudomorph with Quartz

specimen number:
8311448

location:
Poudrette Quarry, Mt. St. Hilaire, Quebec, Canada

description:
A large thick prismatic crystal of what was once aegirine now replaced by an unknown mineral. Small crystals of quartz are scattered throughout.

The Poudrette Quarry, located on the northern flank of Mont Saint-Hilaire in Quebec, Canada, is an internationally famous mineralogical site situated within an alkaline igneous complex. Geologically, the quarry exposes three distinct intrusive phases of the Monteregian Hills petrographic province, specifically agpaitic nepheline syenites and sodalite syenites that are exceptionally rich in rare earth elements and volatiles. These conditions have resulted in the discovery of over 400 mineral species, including iconic specimens of serandite, catapleiite, and carletonite. Historically, industrial mining and quarrying for crushed stone began in the late 1950s under the Poudrette family, with the site gaining global recognition among collectors and researchers throughout the 1960s and 1970s. While primary operations were centered on aggregate production for decades, the quarry became a world-class destination for systematic mineralogical study and specimen recovery. As of 2026, although commercial quarrying has faced various operational changes and access restrictions, the Poudrette Quarry remains one of the most mineralogically diverse localities on Earth.

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