The Franklin Mine, also known as Franklin Furnace, in Franklin, Sussex County, New Jersey, was active from 1898 until the mid-1950s and is legendary for producing over 350 mineral species—among the highest diversities worldwide—and more fluorescent minerals than any other locality on Earth. The orebody’s unique zinc‐iron‐manganese assemblage yields classic fluorescent specimens such as green-glowing willemite, red-glowing calcite, violet-blue–glowing hardystonite, and yellow-glowing esperite, which collectively earned Franklin the nickname “Fluorescent Mineral Capital of the World”. Today, the Franklin Mine site houses the Franklin Mineral Museum, where visitors can view and collect dazzling fluorescent minerals under UV light and learn about the locale’s amazing mineralogical heritage.