LUDLAMITE, BLACKBIRD MINE, LEMHI COUNTY, IDAHO, USA (thumbnail)

Ludlamite is a unique phosphate mineral characterized by the chemical formula (Fe,Mn,Mg)3(PO4)2·4H2O. It was first identified in 1877 at the Wheal Jane mine in Cornwall, England, and is named after the English mineralogist Henry Ludlam (1824–1880).

This mineral is found in granite pegmatites and forms as a hydrothermal alteration product of earlier phosphate minerals in reducing environments. It is commonly associated with minerals such as whitlockite, vivianite, triploidite, triplite, triphylite, siderite, phosphoferrite, fairfieldite, and apatite.