Giorgiosite - Germany, Saxony-Anhalt, Hettstedt - 1 mm. Photos from tomeikminerals.com can be used under a Creative Commons Licenese 4.0 CC-BY, as explained in: https://www.tomeikminerals.com/about-me . — Photo: Henk Smeets - Tomeik Minerals · CC BY 4.0
Giorgiosite
Giorgiosite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Mg₅(CO₃)₄(OH)₂·5H₂O.
Key properties: specific gravity 2.15–2.19; Silky luster; optically biaxial.
IMA symbol Gio, IMA status: questionable, named in 1905.
A rare incrustation on recent lava (Thı́ra Island, Greece); a weathering product in fractures in sideritic iron formation (Big Fish River-Rapid Creek area, Canada).
It is found associated with Sodium chloride, sodium sulfate, magnesium carbonate (Thı́ra Island, Greece); aragonite, kulanite (Big Fish River-Rapid Creek area, Canada).
The name refers to Giorgios, a cone formed during the volcanic eruption of 1866 on Thı́ra Island.