Garronite (Size ~ ½ mm) Locality: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, Rouville RCM, Montérégie, Québec, Canada "Pebbly" garronite pseudo-octahedra to ~ ½ mm. MOB coll. These are the bluest xls on the specimen. Most of it is gray or gray/blue - see one the stereo child photos using half the magnification. — Photo: Modris Baum · Public domain
Garronite-Na
Garronite-Na is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₆(Al₆Si₁₀O₃₂)·8.5H₂O.
It crystallizes in the monoclinic crystal system (space group I2). It is a member of the Gismondine structural group.
Key properties: Mohs hardness 4; specific gravity 2.19; White streak; Vitreous; frosted aggregates luster; optically biaxial.
IMA symbol Grn-Na, IMA status: approved, named in 2015.
Found in vugs in a hydrothermally-altered zone of the Poudrette pegmatite and in sodalite-rich segregations in nepheline syenite both part of an alkaline igneous intrusive complex. Association Natrolite, gmelinite, aegirine, gonnardite.
The suffix indicates the Na analog of garronite.