Ludlamite
Ludlamite is a rare phosphate mineral with formula: (Fe,Mn,Mg)3(PO4)2·4H2O.
| Ludlamite | |
|---|---|
 | |
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | (Fe,Mn,Mg)3(PO4)2·4H2O |
| Strunz classification | 8.CD.20 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| Unit cell | a = 10.541(5), b = 4.646(4) c = 9.324(5) [Å]; β = 100.52°; Z = 2 |
| Identification | |
| Color | Apple-green to bright green |
| Crystal habit | Tabular crystals; massive, granular |
| Cleavage | Cleavage: perfect on {001}, indistinct on {100} |
| Mohs scale hardness | 3.5 |
| Luster | Vitreous, pearly on cleavage |
| Streak | Pale greenish white |
| Diaphaneity | Translucent |
| Specific gravity | 3.12–3.19 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.650 - 1.653 nβ = 1.669 - 1.675 nγ = 1.688 - 1.697 |
| Birefringence | δ = 0.038 - 0.044 |
| 2V angle | Measured: 82° |
| References | [1][2][3] |
It was first described in 1877 for an occurrence in Wheal Jane mine in Cornwall, England and named for English mineralogist Henry Ludlam (1824–1880).
Occurrence
It occurs in granite pegmatites and as a hydrothermal alteration product of earlier phosphate bearing minerals in a reducing environment.[3] It occurs associated with whitlockite, vivianite, triploidite, triplite, triphylite, siderite, phosphoferrite, fairfieldite and apatite.[1]
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References
External links
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