Franklinite is named after the locality of Franklin, New Jersey, where it is found. It is only found in Franklin and the neighboring town of Ogdensburg, in Sussex Co., New Jersey. There are no other localities for this mineral, but in those two localities it is fairly common. However, the large crystals of the past are no longer found and are well sought-after by collectors.
Franklinite is usually associated with brilliantly fluorescent Calcite and Willemite, and may also occur with orange Zincite, providing specimens of nice color contrasting. Franklinite is sometimes classified as a variety of the mineral Magnetite, but it is in fact a distinct mineral species.