Formula: Fe2+3(PO4)2.4H2O
Hydrated normal phosphate, ludlamite group
Specific gravity: 3.12 to 3.19
Hardness: 3½
Streak: Pale greenish white
Colour: Apple-green to bright green, nearly colourless in transmitted light, rarely blue
Solubility: Soluble in acids

Hydrothermal environments

Ludlamite occurs as a secondary phosphate in complex granite pegmatites as a common hydrothermal alteration product of earlier phosphates, formed under reducing conditions; it is also found in polymetallic veins (Mindat, HOM). Common associates include fairfieldite, fluorapatite, phosphoferrite, siderite, triphylite, triplite, triploidite, vivianite and whitlockite (Mindat)


At Hagendorf, Germany, ludlamite is associated with phosphoferrite, triploidite, triplite, triphylite and apatite (HOM).

At the type locality, Wheal Jane, Baldhu, Kea, Cornwall, England, UK, ludlamite occurs in copper-tin veins associated with granite intrusives, associated with sphalerite, quartz and pyrite (Mindat)

At the Chickering mine in Walpole, Cheshire county, New Hampshire, USA, ludlamite most commonly appears in intermediate to late-stage, hydrothermally altered triphylite. It is common and occurs with siderite, quartz, albite, beraunite, messelite, strunzite, whitmoreite and vivianite (R&M 90.5.419).

In the Blackbird district, Lemhi County, Idaho, USA, ludlamite has been found in copper-cobalt deposits intimately associated with vivianite, pyrite, quartz, calcite and siderite. It occurs in vugs and in veinlets in sulfide ore consisting of pyrrhotite, chalcopyrite, pyrite and cobaltite, along with minor minerals including safflorite, tourmaline, apatite, mica and carbonates (AM 34.335, Minrec 41.4.363-369).

At the Palermo mine, North Groton, New Hampshire, USA, ludlamite has been found in crystals to 2 mm in small veins and in large masses in triphylite. In small cavities within the veinlets additional phosphates such as fairfieldite are found coating the ludlamite. Vivianite occurs on the fairfieldite as separate crystals. Reddingite occurs in very small crystals on the ludlamite. The triphylite is altered to ludlamite (AM 34.94-97). Other associated minerals include phosphoferrite, triphylite, siderite, whitlockite, hydroxylapatite and carbonates (Dana, HOM).

Back to Minerals