Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Cubic
    Chemistry : ZnFe₂O₄
    Rarity : Rare to very rare

Franklinite belongs to the group of spinels with a normal structure. It is a rare mineral present in zinc-bearing metal deposits that have undergone contact metamorphism. It combines with zincite and willemite. It can also be found in certain slags. It owes its name to its location of discovery : the Franklin mine (New Jersey, USA) and also to honor the name of Benjamin Franklin, politician, physicist and inventor of the lightning rod who gave its name to the city. Franklinite occurs in granular or compact masses like magnetite, rarely in octahedral crystals with often rounded faces. Its luster is metallic, sometimes dull, its color brown-black to black. It is occasionally a zinc ore.

Main photo : 5 cm edged franklinite from Franklin Mine, Franklin, Sussex County, New Jersey, USA © Rock Currier

Twins are known on {111}.

No fakes recorded for this mineral species.