| Ludlamite | |
| Category: | Phosphate mineral |
| Imasymbol: | Lud[1] |
| Strunz: | 8.CD.20 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | 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 |
| Habit: | Tabular crystals; massive, granular |
| Cleavage: | Cleavage: perfect on, indistinct on |
| Mohs: | 3.5 |
| Luster: | Vitreous, pearly on cleavage |
| Streak: | Pale greenish white |
| Diaphaneity: | Translucent |
| Gravity: | 3.12–3.19 |
| Opticalprop: | Biaxial (+) |
| Refractive: | nα = 1.650 - 1.653 nβ = 1.669 - 1.675 nγ = 1.688 - 1.697 |
| Birefringence: | δ = 0.038 - 0.044 |
| 2V: | Measured: 82° |
| References: | [2] [3] [4] |
Ludlamite is a rare phosphate mineral with chemical formula . 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.[4] It occurs associated with whitlockite, vivianite, triploidite, triplite, triphylite, siderite, phosphoferrite, fairfieldite and apatite.[2]