Gobbinsite , Gmelinite-Na (FOV 6.8 x 4.6 mm) Locality: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, Rouville RCM, Montérégie, Québec, Canada Found June 1997. MOB coll. From the Poudrette pegmatite contact zone area. This one has a rather dark rosette of gmelinite-Na sitting on it. This is a common combination. — Photo: Modris Baum · Public domain
Gobbinsite
Gobbinsite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₅(Si₁₁Al₅)O₃₂·11H₂O.
It crystallizes in the orthorhombic crystal system (space group Pmn2_1). It is a member of the Gismondine structural group.
Key properties: Mohs hardness 4; specific gravity 2.194; White streak; optically uniaxial.
IMA symbol Gbb, IMA status: approved, named in 1980.
Found as a secondary mineral in amygdules in basalts (Co. Antrim, Ireland); in cavities in sodalite syenite in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).
It is found associated with Gmelinite, calcite (Co. Antrim, Ireland); tetranatrolite, s¶erandite (Mont Saint-Hilaire, Canada).
The name is taken from the type locality at The Gobbins, Ireland.