Calcite with Franklinite, Willemite

specimen number:
2072336

location:
Franklin, Sussex Co., New Jersey, USA

description:
Massive calcite hosting small crystals of franklinite and minor willemite throughout. Brightly fluorescent. Classic material.

The Franklin Mine, located in Franklin, Sussex County, New Jersey, is one of the most famous mineral localities in the world, situated within the Reading Prong of the Highlands physiographic province. Geologically, the deposit is a unique Precambrian stratiform zinc-iron-manganese ore body hosted in the Franklin Marble, where high-grade metamorphic processes transformed original sediments into a complex mineral assemblage found nowhere else on Earth. The site is most celebrated for its spectacular fluorescent mineral combinations, primarily consisting of calcite, willemite, and franklinite; under short-wave ultraviolet light, the calcite fluoresces a brilliant cherry-red and the willemite a vibrant neon-green, while the black, metallic franklinite remains non-fluorescent, creating a striking visual contrast. Historically, mining and quarrying in the Franklin area began as early as the mid-1600s with iron exploration, but major industrial zinc production commenced in the mid-19th century and continued until the mine was officially exhausted and closed in 1954. As of 2026, the locality is preserved through the Franklin Mineral Museum, which maintains the historic Buckwheat Dump, allowing for the continued study and recovery of these world-renowned fluorescent specimens from the historic tailings.

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