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Formula: KCa(H3O)3(U6+O2)7(PO4)4O4.8H2O
Phosphate, uranyl mineral,
phosphuranylite group
Crystal System: Orthorhombic
Specific gravity:
Hardness: 2½
Streak: Pale yellow
Colour: Bright yellow; deep golden-yellow, honey-yellow
Luminescence: Not fluorescent, but samples may fluoresce due to admixed autunite, etc.
Environments
Pegmatites
Sedimentary environments
Phosphuranylite is a secondary mineral typically occurring
in the weathering zone of
pegmatites, coating cracks and fissures near altered
uraninite, and in paleochannels (ancient, currently inactive river and stream
channels) in sandstone
uranium-vanadium deposits. Associated
minerals include uraninite,
autunite, meta-autunite,
uranophane, parauranophane,
becquerelite, curite,
parsonsite, torbernite,
metatorbernite, saleeite,
sabugalite, haiweeite and
uranium-bearing opal
(HOM).
Phosphuranylite typically forms earthy to scaly crusts of minute deep golden yellow crystals. The most common
mode of occurrence is an alteration product of uraninite in radioactive
pegmatites
(Lauf2).
Localities
At the Mamões pegmatite, Equador, Rio Grande do Norte, Brazil, phosphuranylite occurs as crystalline to earthy
films on quartz with meta-autunite
and unidentified uranium minerals
(AM 35.756-763).
At Pamplonita, Norte de Santander Department, Colombia, phosphuranylite occurs as earthy films on massive
quartz with meta-autunite. Other
specimens from this locality show uraninite altering to
curite, schoepite,
becquerelite and unidentified minerals
(AM 35.756-763).
At the Wölsendorf fluorite mining district, Upper Palatinate, Bavaria, Germany, a specimen was found that is a mass of
purple-black fluorite, hematite and
quartz with fine-grained crusts of a yellow mineral that is a mixture of
dewindtite and lead-bearing
phosphuranylite
(AM 35.756-763).
At the Rosmaneira Mine, Bendada, Sabugal, Guarda, Portugal, phosphuranylite occurs as a thick flaky coating on a
slab of deeply altered (?)granite
(AM 35.756-763).
At the Carrasca Mine, Quarta-Feira, Sortelha, Sabugal, Guarda, Portugal, veinlets of flaky phosphuranylite cut a
slab of altered granite whose outer surfaces are thickly encrusted with
meta-autunite. The phosphuranylite is mixed with altered
meta-autunite
(AM 35.756-763).
At the Urgeiriça Mines, Canas de Senhorim, Nelas, Viseu, Portugal, a specimen was found which was a mass of
limonitic quartz with drusy cavities
containing citron-yellow to brownish yellow microscopic laths and needles mostly clustered on crystals of a related
mineral. The mixture probably represents an intergrowth of lead-bearing
phosphuranylite with dewindtite
(AM 35.756-763).
At the Fillow Quarry (Branchville Quarry), Branchville, Redding, Fairfield County, Connecticut, USA,
phosphuranylite
occurs as films and veinlets in altered uraninite
(AM 35.756-763).
At Newry, Oxford County, Maine, USA, a large book of muscovite was found
containing quartz and uraninite along
the margins and coated with phosphuranylite along fracture surfaces and in opened cleavages of the
mica
(AM 35.756-763).
At the Ruggles Mine, Grafton, Grafton County, New Hampshire, USA, phosphuranylite was found as films and coatings
in fractures and cavities in quartz and
feldspar, usually near the gummite
pseudomorphs after uraninite
for which the locality is noted. The phosphuranylite is found with
meta-autunite, parsonsite and
a number of other secondary
uranium minerals. Both phosphuranylite and
meta-autunite are particularly abundant at the Ruggles
pegmatite, where
apatite occurs in large amounts as a
primary mineral immediately associated with
uraninite
(AM 35.756-763).
Phosphuranylite from the Ruggles Mine - Image
At the Palermo mine, North Groton, Grafton County, New Hampshire, USA, coatings of phosphuranylite occur with
meta-autunite on aggregates of
quartz, muscovite and
kaolinised feldspar containing
gummite pseudomorphs
(AM 35.756-763).
At Bedford Hills, Westchester County, New York, USA, phosphuranylite occurs as minutely crystalline films on
feldspar and quartz, with fluorescent
hyalite
(AM 35.756-763).
The type locality is the Buchanan Mine (Buchanan pegmatite),
Mitchell County, North Carolina, USA.
The Flat Rock Mine (Flat Rock pegmatite), Mitchell county,
North Carolina, USA, has produced specimens of of smoky or milky quartz,
feldspar, muscovite and
garnet coated by films of phosphuranylite and
meta-autunite. One specimen showed cubical molds of
uraninite crystals partly filled with phosphuranylite
(AM 35.756-763).
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