Chalcophanite

specimen number:
2262304

location:
Sterling Hill, New Jersey, USA

description:
Black masses of chalcophanite throughout matrix.

The Sterling Hill mine, located in Ogdensburg, Sussex County, New Jersey, was a world-famous underground zinc mining operation renowned for its complex mineralogy and abundant fluorescent minerals. Geologically, the deposit is a highly unusual, stratiform body hosted within the Proterozoic-age Franklin Marble formation, where ancient zinc, manganese, and iron sediments underwent intense granulite-facies regional metamorphism. This unique geologic history created a massive, folded ore body dominated by zinc silicates and oxides, specifically willemite, zincite, and franklinite, completely lacking the common lead and sulfur compounds found in typical zinc deposits. Historically, the outcrop was discovered by early colonists in the 1700s and initially mistaken for iron or copper ore before its unique zinc chemistry was properly understood in the early 1800s. Large-scale corporate underground mining began in earnest during the mid-nineteenth century and was eventually consolidated under the New Jersey Zinc Company, which sank deep vertical shafts to extract millions of tons of high-grade zinc ore through the twentieth century. Commercial extraction continued almost uninterrupted until economic depletion and high operating costs led to the permanent cessation of all mining operations at the site in March 1986, after which the facility was preserved and opened as a mining museum.

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