Arsenuranospathite

arsenuranospathite

ianthinite

uranocircite

metakirchheimerite

Images

Formula: Al(UO2)2(AsO4)2F.20H2O
Hydrated arsenate, uranyl mineral
Crystal System: Orthorhombic
Specific gravity: 2.54 calculated
Hardness: 2
Streak: White
Colour: Pale yellow
Luminescence: Weak greenish fluorescence under short wave UV
Solubility: Readily partially dehydrates in air
Common impurities: P
RADIOACTIVE
Environments

Sedimentary environments
Hydrothermal environments

Arsenuranospathite occurs very rarely as a secondary mineral in uranium deposits. Associated minerals include zeunerite, uranophane, studtite, uranospinite, ianthinite, metakirchheimerite, uranocirciteheinrichite, baryte and limonite (HOM).

Localities

The type locality is the Sophia Mine, Böckelsbach valley, Wittichen, Schenkenzell, Rottweil, Freiburg Region, Baden-Württemberg, Germany.

At the Krunkelbach Valley Uranium deposit, Menzenschwand, St Blasien, Waldshut, Freiburg Region, Baden-Württemberg, Germany, arsenuranospathite was found among the secondary minerals of the uranium deposit in crusts on baryte. It is associated with limonite and secondary uranium minerals, such as zeunerite, mixed crystals of the uranocircite-heinrichite series, uranophane and studtite. The arsenuranospathite crusts are composed of minute tabular crystals, of maximum length about 0.3 mm. Almost a needle-like habit results if the elongation is pronounced (MM 42.117-128).
Arsenuranospathite from the Krunkelbach Valley uranium deposit - Image

At the Zimná Voda uranium occurrence, Prakovce, Gelnica District, Košice Region, Slovakia, assemblages of supergene minerals occur in hydrothermal REE–U–Au quartz-vein mineralisation. Heterogeneous uranyl arsenates and minor phosphates of the autunite group (nováčekite, kahlerite, threadgoldite, autunite, arsenuranospathite and chistyakovaite) together with scorodite and Sb–Bi-rich philipsbornitesegnitite series minerals formed by oxidising fluids during decomposition and leaching of primary hypogene uraninite, brannerite and base-metal sulphides and sulphosalts. A progressive change of pH from acidic to near-neutral due to the gradual consumption of sulphides resulted in the formation of late phosphuranylite, pharmacosiderite and arseniosiderite. Goethite and other Fe oxides represent the latest hydrous ferric mineral phases and were formed after most of the As was already fixed in Fe arsenates. Antimony and bismuth were taken up only into philipsbornitesegnitite and suggest unusual conditions during this process (MM 87.6.849–865).

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