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, childrenite–eosphorite, laueite, strunzite, stewartite, mitridatite, amblygonite and siderite.[2]
| 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 | [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]
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