ludlamite

{{infobox mineral | name = Ludlamite | image = Ludlamite-md87a.jpg | imagesize = 200px | alt = | caption = | category = Phosphate mineral | formula = | IMAsymbol = Lud | molweight = | strunz = 8.CD.20 | dana = | 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 | colour = | habit = Tabular crystals; massive, granular | twinning = | cleavage = Cleavage: perfect on {001}, indistinct on {100} | fracture = | tenacity = | mohs = 3.5 | luster = Vitreous, pearly on cleavage | streak = Pale greenish white | diaphaneity = Translucent | gravity = 3.12–3.19 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.650 - 1.653 nβ = 1.669 - 1.675 nγ = 1.688 - 1.697 | birefringence = δ = 0.038 - 0.044 | pleochroism = | 2V = Measured: 82° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | references = }}

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).