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Category Phosphate mineral
(repeating unit)
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
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]

Ludlamite is a rare phosphate mineral with formula: (Fe,Mn,Mg)3(PO4)2·4H2O.

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).


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]


External links[edit]

Media related to ludlamite at Wikimedia Commons