During the X-ray study of a new phosphate mineral, not yet published, the usual comparison was made with cell-side measuremerits of related minerals. One of these is ‘eggonite’, a rare hydrous aluminium phosphate said to occur on silver ores at Felsőbánya, Hungary. Rotation photographs of ‘eggonite’ are different from those of the new mineral, but yielded dimensions close to those of sterrettite, a new mineral from Fairfield, Utah, described last year by Larsen and Montgomery. These authors generously presented a specimen of sterrettite to the British Museum, and rotation photographs taken in the Mineral Department not only give cell-dimensions close to those published but also identical with those of ‘eggonite’. A brief account of this identification is now given not only to justify abandoning the mineral name ‘eggonite’, but also to place on record a European occurrence of a rare mineral so far described from only one American locality.