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Formula: Ca9(UO2)4(CO3)13.28H2O
Hydrated carbonate, markeyite group,
uranyl mineral
Crystal system: Orthorhombic
Specific gravity: 2.68 measured, 2.699 calculated for the empirical formula
Hardness: 1½ to 2
Streak: White
Colour: Pale yellowish green
Luminescence: Fluorsces bright bluish white under a 405 nm laser
Solubility: At room temperature, dissolves very slowly in water (minutes) and dissolves immediately with
effervescence in dilute hydrochloric acid
RADIOACTIVE
Environments
Sedimentary environments
Hydrothermal environments
Markeyite is a relatively new mineral, approved in 2016 and to date (September 2025) reported only from the
type locality.
Localities
At the type locality, the Markey Mine, Red Canyon Mining District, San Juan County, Utah, USA, markeyite was
found underground. The geology of the Markey mine is quite similar to that of the nearby (1 km away) Blue Lizard
mine, although the secondary mineralogy of the Markey mine is
notably richer in carbonate phases.
The uranium deposits in Red Canyon occur in channels incised into the
reddish brown siltstones of the underlying formation. Ore minerals
were deposited as replacements of wood and other organic material and as disseminations in the enclosing
sandstone. Since the mine closed in 1982, oxidation of
primary ores in the humid underground environment has
produced a variety of secondary minerals, mainly carbonates
and sulphates, as efflorescent crusts on the surfaces of mine walls.
Markeyite is a rare mineral in the secondary mineral
assemblage. It occurs on asphaltum (bitumen) in association with calcite,
gypsum and natrozippeite.
Other secondary minerals in the general assemblage include
ammoniozippeite,
andersonite, anglesite,
aragonite,
arsenuranospathite,
atacamite, bayleyite,
bluelizardite,
bobcookite, brochantite,
čejkaite, chalcanthite,
chalconatronite,
chinleite-(Y), covellite,
cuprosklodowskite,
cyanotrichite, deliensite,
devilline, erythrite,
eugsterite, fermiite,
jarosite, johannite,
klaprothite,
leószilárdite, leydetite,
magnesioleydetite,
mahnertite, malachite,
marécottite, melanterite,
metakahlerite,
metasideronatrite,
natrojarosite, plášilite,
posnjakite,
pseudojohannite,
redcanyonite, römerite,
sabugalite,
schröckingerite,
sideronatrite, sulphur,
thénardite,
thérèsemagnanite,
uramarsite, uranospathite,
wetherillite and zippeite.
Markeyite crystals occur as blades and tablets up to about 1 mm in maximum dimension
(MM 82.5.1089-1100).
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