Franklinite is a rare mineral found in the zinc mines of Franklin, New Jersey. It is known for its magnetic properties and distinctive black color. As with many minerals, there are multiple synonyms for Franklinite, including Franklinfurnaceite, Franklinite variety Magnesiofranklinite, Magnesiofranklinite, and Zwieselite. These synonyms refer to variations of the original mineral composition or locality, and can be used interchangeably with the name Franklinite. Although it has limited industrial uses, Franklinite is highly sought after by mineral collectors and can fetch high prices due to its rarity and unique properties.