Tyuyamunite

tyuyamunite

carnotite

metatyuyamunite

volborthite

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Formula:Ca(UO2)2(VO4)2.5-8H2O
Hydrated normal vanadate, carnotite group
Specific gravity: 3.57 to 4.35
Hardness: 1½ to 2
Streak: Light yellow
Colour: Canary yellow, lemon-yellow; greenish yellow (upon exposure to sunlight); colourless to pale yellow in transmitted light
Solubility: Insoluble in dilute acetic acid; soluble in hydrochloric, nitric and sulphuric acids
RADIOACTIVE
Environments

Sedimentary environments

Tyuyamunite is an uncommon secondary vanadate occurring in the oxidised zones of uranium-vanadium deposits, especially those of the Colorado Plateau type (Mindat, Webmin, HOM). Associated minerals include metatyuyamunite, carnotite, corvusite, uranophane, volborthite and gypsum (HOM, Mindat).

Localities

At the type locality, the Tyuya-Muyun Cu-V-U deposit, Aravan District, Osh Region, Kyrgyzstan, tyuyamunite occurs in Carboniferous limestone associated with turanite, malachite, calcite and baryte (Mindat).

At the Cripple creek mining district, Colorado, USA, tyuyamunite has been reported associated with fluorite, talc, kaolinite and gypsum (Minrec 36.2.182).

Alteration

Tyuyamunite easily dehydrates in a dry atmosphere to metatyuyamunite (Mindat).

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