Specimen of the mineral scarbroite (white) with allophane (blue). Roadcut in the road to San Pedro Manrique, Magaña (Soria) Spain — Photo: Bergminer · CC BY-SA 4.0
Scarbroite
Scarbroite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Al₅(CO₃)(OH)₁₃·5H₂O.
It crystallizes in the triclinic crystal system.
Key properties: specific gravity 2.01; Dull luster.
IMA symbol Scr, grandfathered status — known before the IMA’s founding, named in 1829.
Found in vertical fissures in sandstone (Scarborough, England); authigenic, probably formed by dessication of near-shore bottom sediments of a hypersaline lake (Muskiki Lake, Canada).
It is found associated with Hydroscarbroite, gibbsite, kaolinite, calcite, quartz (Scarborough, England); illite, kaolinite, smectite, “chlorite”, huntite, feldspar, quartz (Muskiki Lake.
The name refers to its first-noted occurrence near Scarborough [contracted to Scarbro, the common local pronunciation], England.