Hopeite is a hydrated with formula: Zn3(PO4)2·4H2O. It is a rare mineral used mainly as a collectors specimen.
Hopeite crystallizes in the orthorhombic system with prismatic white to yellow crystals. It also forms druzy encrustations and reniform (kidney-shaped) masses. The related mineral parahopeite, which has the same composition but different crystal structure, is triclinic. The minerals are formed through oxidation of sphalerite by the presence of phosphate-rich solutions
It was first described in 1822 from Moresnet, Liège Province, Belgium chemist, Thomas Charles Hope (1766–1844) of the University of Edinburgh.
It has been found in Zambia.
Hopeite is one of the 2 conversion minerals arising from the application of the rust converter 'Fertan'.