Wetherillite

wetherillite

bobcookite

dietrichite

pickeringite

Images

Formula: Na2Mg(UO2)2(SO4)4.18H2O
Hydrated sulphate, uranyl mineral
Crystal system: Monoclinic
Specific gravity: 2.626 calculated for the empirical formula, 2.563 for the ideal formula
Hardness: 2
Streak: White
Colour: Pale greenish yellow
Solubility: Easily soluble in water at room temperature
Common impurities: Zn,Cu,Fe
RADIOACTIVE
Environments

Hydrothermal environments

Wetherillite is a relatively new mineral, approved in 2014.

Localities

At the type locality, the Blue Lizard Mine, Red Canyon Mining District, San Juan County, Utah, USA, ore minerals (especially uraninite, and the sulphides pyrite, chalcopyrite, bornite and covellite) were deposited as replacements of wood and other organic material and as disseminations in the enclosing sandstone. Since the mine closed in 1978, oxidation of primary ores in the humid underground environment has produced a variety of secondary minerals, mainly sulphates, as efflorescent crusts on the surfaces of mine walls. The vast majority of the secondary minerals contain essential Na, but the source of the Na enrichment is not known.
Bobcookite and wetherillite occur together with other secondary minerals including boyleite, chalcanthite, dietrichite, gypsum, hexahydrite, johannite, pickeringite and rozenite. The bulk of the matrix consists of quartz crystals that are recrystallised counterparts of the original grains of the sandstone. Other minerals remaining from the original sandstone include feldspar, rare almandine and zircon. Minerals related to the ore deposition include baryte, bornite, chalcopyrite, covellite, pyrite and uraninite. Other secondary minerals in the general assemblage include aluminocoquimbite, atacamite, belakovskiite, blödite, bluelizardite, brochantite, calcite, cobaltoblödite, copiapite, coquimbite, cyanotrichite, d’ansite-(Mn), dickite, epsomite, fermiite, ferrinatrite, gerhardtite, gordaite, halite, kieserite, kröhnkite, lishizhenite, manganoblödite, meisserite, metavoltine, natrozippeite, oppenheimerite, plasilite, pseudojohannite, rhomboclase, römerite, sideronatrite and tamarugite.
Wetherillite commonly occurs as pale greenish yellow prisms or blades with irregular terminations up to ~1 mm long in subparallel intergrowths, divergent sprays and jackstraw aggregates. The crystals are transparent with a vitreous lustre (MM 79.3.695-714).
Wetherillite from the Blue Lizard Mine - Image

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