Markeyite

markeyite

calcite

gypsum

natrozippeite

Images

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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