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Formula: Mn2+Al(PO4)(OH)2.H2O
Hydrated phosphate containing hydroxyl, manganese-bearing mineral, forms a series
with childrenite
Crystal System: Orthorhombic
Specific gravity: 3.06 to 3.08 measured, 3.04 calculated
Hardness: 5
Streak: White
Colour: Usually pale brown, golden brown, also medium brown to dark brown, occasionally pink or rose red
Solubility: Soluble in acids
Common impurities: Fe
Environments:
Eosphorite is a secondary mineral in some phosphate-bearing granite
(Webmin,HOM).
Common associates are fairfieldite and
siderite
(Mindat).
Localities
At the type locality, the Fillow Quarry, Branchville, Redding, Fairfield county, Connecticut, USA, eosphorite occurs in a
granite pegmatite, associated with
rhodochrosite, lithiophilite,
triploidite and dickinsonite
(Dana, Mindat, HOM).
At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, eosphorite occurs as an alteration product of
lithiophilite associated with
montebrasite.
(R&M 94.6.507).
At Newry, Oxford county, Maine, USA, eosphorite is associated with albite,
cookeite, apatite,
beryllonite, hydroxylherderite and
tourmaline
(HOM).
The Consolidated quarry in Georgetown, Sagadahoc county, Maine, USA, is a granite
pegmatite with lithium-rich zones. These contain cavities that may produce
tourmaline
and spodumene in association with lepidolite,
beryl, fluorapatite,
montebrasite, cassiterite, and
columbite-tantalite group minerals. In a
mineralised zone rich in albite, muscovite and
beryl; some cavities were opened that mainly contained
quartz crystals, beryl crystals to 10 cm,
albite, microcline and
muscovite. Many of these minerals were overgrown by eosphorite crystals to 3 mm.
In addition, the interior portions of several of the beryl
crystals exhibit alteration to secondary beryllium phosphates.
Hydroxylherderite crystals to 2 cm are locally abundant and are typically
coated by eosphorite crystals. The origin of the eosphorite is problematic, as no remnants of
primary phosphate minerals
(triphylite, lithiophilite,
montebrasite-amblygonite,
fluorapatite) were
observed, although montebrasite can be abundant in some parts of the quarry
(R&M 90-3.275).
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