Franklinite with Willemite, Zincite

specimen number:
2262348

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

description:
Rich black masses of franklinite throughout matrix with willemite and zincite. Incredibly fluorescent.

The Franklin mining district, located in Sussex County, New Jersey, is a globally unique zinc deposit famous for its extraordinary mineral diversity and fluorescent species. Geologically, the deposit is hosted within the Precambrian Franklin Marble, where complex Precambrian regional metamorphism and subsequent structural deformation transformed original sedimentary or volcanogenic precursor deposits into massive, stratiform ore bodies. The primary ore consists of an unusual mineral assemblage of franklinite, willemite, and zincite, completely lacking the typical zinc sulfide minerals found elsewhere in the world. Localized iron mining began in the area as early as the 1760s, but systematic exploitation of the complex zinc ores did not scale up until the mid-nineteenth century with the formation of the New Jersey Zinc Company. Modern, large-scale underground operations centered around the Palmer Shaft deployed advanced mining methods to extract millions of tons of high-grade zinc ore until the total exhaustion of the economic ore reserves forced the permanent closure of the historic Franklin mine in April 1954.

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