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Formula: Li1-x(Fe3+,Mn2+)(PO4)
Discredited species
Anhydrous phosphate, forms a series with sicklerite
Crystal System: Orthorhombic
Specific gravity: 3.2 to 3.4
Hardness: 4
Streak: Light brown
Colour: Yellow-brown to dark brown
Solubility: Soluble in acids.
Environments
Pegmatites
Hydrothermal environments
Ferrisicklerite is a secondary mineral which occurs only as a late
hydrothermal alteration product of triphylite and
lithiophilite in complex zoned granite
pegmatites, commonly as rims around partly altered masses or crystals of the unaltered species (Mindat, Webmin, HOM).
Associated minerals include triphylite -
lithiophilite, heterosite,
alluaudite, phosphosiderite and
cyrilovite (HOM).
Ferrisicklerite alters to the heterosite -
purpurite series by oxidation of the Mn2+ to Mn3+ and leaching of
the Li (Mindat, AM 22.875).
The type locality is Sidi Bou Othmane, Jebilet Mountain, Marrakech-Safi Region, Morocco.
At the Chickering mine, Cheshire county, New Hampshire, USA, ferrisicklerite is an alteration product of
triphylite. It occurs together with heterosite
where the parent triphylite has been hydrothermally altered (R&M 90.5.415-416).
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.
Ferrisicklerite has been reported from the dumps of the Keyes No. 2 mine, interlaminated with
triphylite
(R&M 97.4.315).
At Rochester and North Groton, Strafford county, New Hampshire, USA, ferrisicklerite is found in pegmatites associated with
hureaulite, stewartite,
jahnsite and phosphosiderite
(Dana).
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