Gelosaite
Gelosaite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula BiMo⁶⁺₍₂₋₅ₓ₎Mo⁵⁺₆ₓO₇(OH)·H₂O (0 < x < 0.4).
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Not in a structural group, Gelosaite structural group.
Key properties: Mohs hardness 3; specific gravity 5.114; White streak; Adamantine luster.
IMA symbol Gel, IMA status: approved, named in 2009.
A secondary mineral formed in the oxidation zone of bismuth-molybdenum deposits.
It is found associated with Sardignaite, ferrimolybdite, koechlinite, wulfenite, muscovite (Sardinia); bismutite, quartz (Australia).
The mineral was named to honor Mario Gelosa (1947-2006) from Porto Torres, Sardinia, who first found the mineral.