Chalcocite

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A wonderful thumbnail specimen for the species from this famous locality. None lustrous prismatic crystals forming a cluster with little attached matrix. Examples in this quality from the species and locality rarely appear on the market today.The White Pine Mine in Ontonagon County, Michigan, is a major copper mining operation that was developed in the mid 20th century to exploit a large stratiform copper deposit in Precambrian sedimentary rocks of the Nonesuch Shale. Mining began in 1955 and was carried out through extensive underground workings that followed the copper bearing layers. The deposit was notable for its fine grained chalcocite mineralization, which made it different from the native copper deposits of the Keweenaw Peninsula. The mine operated for several decades before closing in 1995, and it remains an important part of the history of copper mining in the United States.