Uranopilite

uranopilite

zippeite

rutherfordine

soddyite

Images

Formula: (UO2)6(SO4)O2(OH)6.14H2O
Hydrated sulphate, uranyl mineral
Crystal System: Triclinic
Specific gravity: 3.7 to 4.0 measured, 3.74 calculated
Colour: Bright yellow, straw-yellow, colourless to light yellow in transmitted light
Solubility: Insoluble in water, soluble in dilute acids
Luminescence: Uranopilite fluoresces bright greenish yellow, in both long and short wave UV
RADIOACTIVE
Environments

Sedimentary environments
Hydrothermal environments

Uranopilite is a secondary mineral and in part at least is of recent formation as an efflorescence on the walls of mine workings. It commonly occurs as a coating on oxidised vein material in which uraninite and sulphides were primary constituents. Gypsum and zippeite are common associates, and other associates include uraninite, johannite, uranophane, soddyite and fourmarierite. The uranopilite forms fragile, small-botryoidal crusts or isolated, globular to reniform incrusting masses of small size. These are composed of tiny lathlike or needlelike crystals that form felted aggregates. It may dehydrate to metauranopilite (AM 37.950-959, HOM).

Localities

At Hottah Lake, Northwest Territories, Canada, uranopilite has been identified as thin coatings on altered pitchblende. This material is relatively fine-grained with a pale yellow colour and a feltlike structure (AM 37.950-959).

At Great Bear Lake, North Slave Region, Northwest Territories, Canada, uranopilite occurs very sparsely as thin, feltlike crusts and films on massive pitchblende. The uranopilite is relatively dense and fine-grained, with a straw-yellow to pale yellow colour and a dull-silky lustre. It is associated with minor amounts of zippeite as golden-yellow crusts, and with tiny radial-fibrous globules of johannite, fourmarierite and erythrite (AM 37.950-959).

There are two co-type localities, Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic and Johanngeorgenstadt, Erzgebirgskreis, Saxony, Germany.

Uranopilite from Jáchymov - Image

At the Jánská vein, Březové Hory deposit, Březové Hory, Příbram, Příbram District, Central Bohemian Region, Czech Republic, phosphate-rich metalodèvite has been found. The vein has been intensively exploited for silver and is noted for its uranium mineralisation. Specimens of massive uraninite and gummite have been found in this vein, along with cuprosklodowskite, metatorbernite, masuyite, wölsendorfite, anglesite, kasolite, zinczippeite and other minerals of the zippeite group, compreignacite, uranopilite, uranophane and widenmannite (CM 48.113-122).

At the Apex Mine, Reese River Mining District, Lander County, Nevada, USA, the No. 1 and No. 2 adits formerly provided rather spectacular specimens of uranopilite associated with zippeite and rutherfordine. Here, uranopilite is present as bright lemon-yellow, flatlying, radiating crystals to 1 mm. The species may occur either directly upon matrix or as a common overgrowth upon earlier-formed rutherfordine (R&M 87.3.276).

Uranopilite from the Apex mine - Image

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