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Formula: Fe2+2(PO4)(OH)
Anhydrous phosphate containing hydroxyl, triplite group, forms a series with
triploidite
Crystal System: Monoclinic
Specific gravity: 3.79 to 3.82 measured, 3.88 calculated
Hardness: 4½ to 5
Streak: White, off-white
Colour: Red-brown to dark brown, green (rare); light brown in transmitted light.
Solubility: Soluble in acids
Environments
Pegmatites
Sedimentary environments
Hydrothermal environments
Wolfeite is a secondary mineral formed by hydrothermal alteration of
triphylite in complex zoned granite pegmatites,
rarely in hydrothermal veins and in phosphatic nodules in shale. Associated minerals include
triphylite, triplite,
hagendorfite, arrojadite and
apatite in pegmatites, and wicksite,
satterlyite and maricite in
shale
(HOM, Mindat).
Localities
At Skrumpetorp, Godegård, Motala, Östergötland County, Sweden, wolfeite occurs with triplite
(Dana).
The type locality is the Palermo Number 1 Mine, Groton, Grafton county, New Hampshire, USA, which is hosted by a
granite pegmatite. Wolfeite was first noticed as a hydrothermal replacement of
triphylite, associated with indistinct veinlets containing
chlorite, sphalerite,
pyrite and arsenopyrite. Further operations in the
quarry exposed a large triphylite crystal that had been partly reworked hydrothermally into
a granular aggregate composed of residual triphylite,
siderite, quartz,
apatite, plagioclase,
ludlamite and wolfeite
(AM 34.692-698).
At the Keyes Mica Quarries, Orange, Grafton County, New Hampshire, USA, the
pegmatites are beryl-type
rare-element (RE) pegmatites.
The Number 1 mine exposed a pegmatite that shows the most
complex zonation and diverse mineralogy of any of the Keyes
pegmatites. Six zones are distinguished, as follows, proceeding
inward from the margins of the pegmatite:
(1) quartz-muscovite-plagioclase
border zone, 2.5 to 30.5 cm thick
(2) plagioclase-quartz-muscovite
wall zone, 0.3 to 2.4 metres thick
(3) plagioclase-quartz-perthite-biotite
outer intermediate zone, 0.3 to 5.2 metres thick, with lesser muscovite
(4) quartz-plagioclase-muscovite
middle intermediate zone, 15.2 to 61.0 cm thick
(5) perthite-quartz inner intermediate zone, 0.9 to 4.6 meters thick
(6) quartz core, 1.5 to 3.0 metres across
The inner and outer intermediate zones contained perthite crystals up to
1.2 meters in size that were altered to vuggy
albite-muscovite with
fluorapatite crystals. This unit presumably was the source of the
albite, muscovite,
fluorapatite, quartz and other
crystallised minerals found in pieces of vuggy albite
rock on the dumps next to the mine.
The middle intermediate zone produced sheet mica with accessory minerals including
tourmaline, graftonite,
triphylite, vivianite,
pyrite, pyrrhotite, and
beryl crystals to 30.5 cm long and 12.7 cm across.
Wolfeite occurs here with triphylite
(R&M 97.4.327).
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