Wolfeite

wolfeite

triploidite

triplite

triphylite

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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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