Donnayite-(Y) , Ewaldite Locality: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada FOV = 1.96 x 1.53 mm Collected 5/25/91. Associated minerals: calcite, pyrite, fluorite. 32 frames with Zerene Stacker DMap method. — Photo: Jerry Cone · Public domain
Ewaldite
Ewaldite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Ba(Na,Ca,Y,Ce,K)(CO₃)₂·2.6H₂O.
It crystallizes in the hexagonal crystal system (space group P6_3mc).
Key properties: specific gravity 3.25; optically uniaxial.
IMA symbol Ew, IMA status: approved, named in 1969.
From drill core into trona beds in dolomitic marlstone (Green River Formation, Wyoming, USA); from carbonatites and hydrothermal veins in alkaline igneous rocks (Kola Peninsula, Russia).
It is found associated with Mckelveyite-(Y), shortite, labuntsovite, leucosphenite, searlesite, hematite (Green River Formation, Wyoming, USA); kukharenkoite-(Ce), belovite, fluorite.
The mineral was named to honor Professor Paul Peter Ewald (1888–1985), German physicist and crystallographer, founder of Zeits. Krist. and Acta Cryst., Polytechnic Institute of New York, Brooklyn.