- Thomasclarkite-(Y) (type locality) with Adamsite-(Y), and Aegirine on Albite
- Thumbnail, 1.5 x 1.25 x 0.5 cm
- Poudrette quarry, Mont Saint-Hilaire, La Vallee-du-Richelieu RCM, Monteregie, Quebec, Canada
- Ex. Paulo Matioli
Two thumbnails from the type locality! Yellowish white, stubby prismatic crystals thomasclarkite-(Y) to 2 mm in albite with green-black, acicular crystals of aegirine and small, white, acicular, pearly adamite-(Y). Thomasclarkite-(Y) is a complex hydrated rare earth carbonate found only in the alkaline intrusive complex at Mont Sainte-Hilaire, Quebec. The mineral is named in honor of Thomas Henry Clark who was a geology professor at McGill University in Montreal, Quebec. Ex. Paulo Matioli collection.