allophane
/ˈaləfeɪn/Mineralogy
noun
An amorphous clay mineral, typically pale blue, consisting essentially of hydrated aluminium silicate.
Origin
Early 19th century; earliest use found in Annals of Philosophy. From allo- + -phane, after German Allophan, itself apparently after Byzantine Greek ἀλλοϕανής, the mineral being so named on account of its unusual appearance.