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Formula: KFe3+2(PO4)2(OH).2H2O
Hydrated phosphate containing hydroxyl, leucophosphite group,
forms a series with tinsleyite
(AJM 71.1.19).
Crystal System: Monoclinic
Specific gravity: 2.948 measured, 2.911 calculated
Hardness: 3½
Streak: White
Colour: White to greenish, buff, yellow-brown, orange-brown, pink, greenish brown, brownish purple
Solubility: Soluble in 1:1 hydrochloric and sulphuric acid (Dana)
Environments
Pegmatites
Hydrothermal environments
Cave deposits
Leucophosphite is formed by the action of solutions derived from bird or bat guano upon
serpentine or earlier iron-bearing minerals; it is also formed from the
hydrothermal
alteration of earlier iron-bearing phosphates in granite pegmatites
(Mindat, Webmin, HOM). Associated minerals include chalcedony,
opal, serpentine minerals and
variscite (Mindat).
Localities
At Northparkes, Kennedy county, New South Wales, Australia, leucophosphite is associated with
goethite, atacamite and
baryte (AJM 10.2.55).
At Broken Hill, Yancowinna county, New South Wales, Australia, leucophosphite is found scattered across
chalcosiderite - turquoise
(AJM 3.1.47).
At the Moculta Phosphate quarry, Angaston, Mount Lofty Ranges, South Australia, leucophosphite is associated with
variscite, wavellite,
minyulite and natrodufrénite
(AJM 17.1.19).
At Tom's quarry, Kapunda, Mount Lofty Ranges, South Australia, leucophosphite is associated with
natrojarosite, wavellite,
meurigite-Na, natrodufrénite,
cacoxenite and morinite (AJM 17.1.19).
At the Fairview Quarry, Robertstown, Mount Lofty Ranges, South Australia, leucophosphite is associated with
turquoise, cyrilovite and
fluellite (AJM 17.1.19).
At the Mount Deverell variscite deposit, Milgun Station, Western Australia, leucophosphite
generally occurs at the margins of veins containing segelerite,
montgomeryite, gordonite,
collinsite, mitridatite and/or
hydroxylapatite. In some cases it completely replaces veins of
variscite. In one specimen it was associated with
mitridatite and cyrilovite. The
variscite deposits are hosted by marine sedimentary rocks
(AJM 20.2.26).
At the type locality, the Ninghanboun Hills, Weelhamby Lake, Western Australia, leucophosphite was found in veinlets in
serpentine, due to the actions of solutions of bird guano on the
serpentine, associated with variscite,
chalcedony and opal (Dana, AM 42.214-221).
At the Sapucaia pegmatite, Minas Gerais, Brazil, Leucophosphite occurs sparingly in close association with
cyrilovite and phosphosiderite lining vugs
in frondelite. phosphosiderite,
cyrilovite, and leucophosphite are
secondary minerals after frondelite
(AM 42.214-221). The leucophosphite from the Sapucaia pegmatite mine represents the first known occurrence of leucophosphite in
a pegmatite (AM42.214-221).
At Bomi hill and Bamputa, western Liberia, leucophosphite is formed as a result of solutions from bat dung (Dana) associated with
strengite and phosphosiderite
(HOM, AM 42.214-221).
At Bethel Church, Pike county, Indiana, USA, leucophosphite is associated with
vivianite,
aluminian strengite, diadochite,
ferrostrunzite and fluorapatite
(HOM).
At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, leucophosphite is rare, but where it occurs it is usually
associated with phosphosiderite. The Emmons pegmatite is an example of a highly
evolved
boron-lithium-cesium-tantalum
enriched pegmatite
(R&M 94.6.510).
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.
Leucophosphite has been found at the Keyes No. 1 mine. where it occurs rarely as platy, colourless to beige
crystals to 1 mm accompanied by jahnsite,
rockbridgeite and strengite or
phosphosiderite
(R&M 97.4.320-321).
At the Tip Top mine, Custer county, South Dakota, USA, leucophosphite is among the latest minerals to form in open pockets in
rockbridgeite, which derives from the hydrothermal reworking of
triphylite (AM 57.397-410), associated with
rockbridgeite and triphylite (HOM).
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