Copper

specimen number:
2102420

location:
West Ridge Mine, Adams Co., Pennsylvania, USA

description:
Interesting locality example with crystalline native copper with minor attached matrix. From the 1960s.

The West Ridge mine, also known as the West Ridge Quarry, is located within the historic Charmian mining district near Blue Ridge Summit in Franklin and Adams counties, Pennsylvania. Geologically, the open-pit industrial operation cuts into the Neoproterozoic-aged Catoctin Formation, a thick volcanic sequence composed primarily of highly durable metabasalt, or altered greenstone. This tough, fine-grained rock contains localized hydrothermally filled vesicles and micro-fissures that carry secondary minerals including native copper, granular epidote, chlorite, and white vein quartz. Industrial quarrying operations at the specific West Ridge pit were managed for decades by Specialty Granules Incorporated (SGI) to extract and crush the dense metabasalt for use as weathered, weather-resistant roofing granules. Active quarrying and rock extraction at the West Ridge pit ceased in 1996, at which point the operation transitioned into a multi-decade reclamation phase involving the structured backfilling of crushed rock fines from nearby active pits to stabilize the quarry rim.

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