Xanthoxenite

Xanthoxenite is a rare calcium iron(III) phosphate mineral with formula: Ca4Fe3+2(PO4)4(OH)2·3H2O. It occurs as earthy pale to brownish yellow incrustations and lath shaped crystals. It crystallizes in the triclinic crystal system. It occurs as an alteration product of triphylite in pegmatites.[3] It occurs associated with apatite, whitlockite, childreniteeosphorite, laueite, strunzite, stewartite, mitridatite, amblygonite and siderite.[2]

Xanthoxenite
General
CategoryPhosphate minerals
Formula
(repeating unit)
Ca4Fe3+2(PO4)4(OH)2·3H2O
Strunz classification8.DH.40
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Unit cella = 6.7 Å, b = 8.85 Å
c = 6.54 Å; α = 92.1°
β = 110.1°, γ = 93.2°; Z = 1
Identification
Formula mass739.95 g/mol
ColorPale to brownish yellow
Crystal habitOccurs as platy crystals and as lamellar aggregates and crusts
CleavagePerfect {010}
Mohs scale hardness2.5
LusterEarthy (dull)
StreakWhite
DiaphaneityTranslucent
Specific gravity2.97 measured, 3.38 calculated
Optical propertiesBiaxial (-)
Refractive indexnα = 1.704 nβ = 1.715 nγ = 1.724
References[1][2][3]

It has been found in Australia, Brazil, Portugal, Spain, Ukraine, and the United States. It was first described in 1920 for an occurrence in North Groton, Grafton County, New Hampshire.[1]

References

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