Xanthoxenite

Xanthoxenite
General
Category	Phosphate minerals
Formula (repeating unit)	Ca4Fe3+2(PO4)4(OH)2·3H2O
Strunz classification	8.DH.40
Crystal system	Triclinic
Crystal class	Pinacoidal (1) (same H-M symbol)
Space group	P1
Unit cell	a = 6.7 Å, b = 8.85 Å c = 6.54 Å; α = 92.1° β = 110.1°, γ = 93.2°; Z = 1
Identification
Formula mass	739.95 g/mol
Color	Pale to brownish yellow
Crystal habit	Occurs as platy crystals and as lamellar aggregates and crusts
Cleavage	Perfect {010}
Mohs scale hardness	2.5
Luster	Earthy (dull)
Streak	White
Diaphaneity	Translucent
Specific gravity	2.97 measured, 3.38 calculated
Optical properties	Biaxial (-)
Refractive index	nα = 1.704 nβ = 1.715 nγ = 1.724
References

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. It occurs associated with apatite, whitlockite, childrenite–eosphorite, laueite, strunzite, stewartite, mitridatite, amblygonite and siderite.

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.