Wetherillite
Wetherillite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Na₂Mg(UO₂)₂(SO₄)₄·18H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 2; specific gravity 2.626; White streak; Vitreous luster; optically biaxial.
IMA symbol Wet, IMA status: approved, named in 2014.
Occurs as efflorescent crusts, on the surfaces of mine walls, derived from the oxidation of primary minerals (uraninite, pyrite, chalcopyrite, bornite and covellite) in a relatively humid underground environment.
It is found associated with Bobcookite, boyleite, chalcanthite, dietrichite, gypsum, hexahydrite, johannite, pickeringite, rozenite.
The mineral was named to honor John Wetherill (1866-1944), discoverer of the deposit that was exploited as the Blue Lizard mine, and for George W.