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Formula: (U6+O2)Bi4O4(PO4)
Hydrated phosphate, uranyl mineral,
walpurgite group,
bismuth-bearing mineral
Crystal System: Triclinic
Specific gravity: 6.36 calculated for the empirical formula
Streak: Light brown
Colour: Brownish grey
Luminescence: Nonfluorescent both under long wave and under short wave UV
Very strongly RADIOACTIVE
Environments
Metamorphic environments
Hydrothermal environments
Phosphowalpurgite is a secondary mineral formed by
weathering of primary
bismuth and uraninite in
hydrothermal quartz veins
(HOM).
Localities
At the type locality, Smrkovec, Březová, Sokolov District, Karlovy Vary Region, Czech Republic, veins of
hydrothermal ore are located in a fault zone between a granite body
and the surrounding metamorphic rocks. This rock complex includes
chlorite–white mica
phyllites, metamorphosed along the
granite contact into two-mica
gneisses and massive
hornfels with
sillimanite, andalusite and
garnet. Phosphorus-rich rocks also occur in this complex. It appears that
the mineralisation is related to thin hydrothermal quartz veins and
alteration zones along those veins where impregnations of bismuth,
bismutite and
bismutoferrite occur.
Primary mineralisation is represented by irregularly
disseminated aggregates of ore minerals, especially bismuth,
galena, silver-bearing sulphides,
nickel-cobalt
arsenides and uraninite, enclosed in
a quartz gangue. Grains of massive
grey sillénite, up to several cm in size and probably of
primary origin were identified sporadically.
Secondary minerals include
metatorbernite, autunite,
zippeite, retgersite,
atelestite, hechtsbergite,
smrkovecite,
preisingerite,
petitjeanite, eulytine,
bismutite, bismutoferrite,
mixite, pucherite and (PO4)-rich
walpurgite.
Phosphowalpurgite occurs as small clusters of irregular crystals, up to 1 cm in size, within small fissures
and cavities in the quartz gangue.
Subhedral to euhedral tabular crystals do not exceed 1 mm in size and average 0.1 to 0.3 mm
(CM 42.4.963-972).
Phosphowalpurgite from Smrkovec - Image
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