Silver with Copper

specimen number:
2062283

location:
White Pine Mine, Ontonogan Co., Michigan, USA

description:

Crystals of native silver measuring to 0.7 cm in size coming off of a matrix which in native copper. The specimen comes with a previous label from the Seaman Mineral Museum at Michigan Tech University. This is shown at the end of the video.

The White Pine mine, located near the Porcupine Mountains in Ontonagon County, Michigan, was a massive underground industrial operation that stood out as the largest known sediment-hosted copper-shale deposit in the United States. Geologically, the ore body is situated within the Iron River syncline and is strictly restricted to the lower 20 to 25 feet of the late Keweenawan-aged Nonesuch Shale, a sequence composed largely of gray siltstone and dark, carbonaceous mudstone. Unlike the native copper deposits found further northeast on the Keweenaw Peninsula, the mineralization at White Pine consists primarily of fine-grained copper sulfide, largely in the form of chalcocite, which is stratigraphically distributed through the parting shale and upper shale layers alongside significant silver byproducts. The deposit was originally discovered in 1865, with initial small-scale underground exploration and trial mining occurring intermittently from 1879 to 1881 and again from 1913 to 1920 under Calumet and Hecla. Large-scale modern development began in March 1952 when the Copper Range Company secured a substantial federal loan to construct a giant, integrated mine, mill, and smelter complex. This major era of production commenced in 1953, reaching peak employment in the mid-1970s and continuing under multiple corporate owners until low metal prices and environmental liabilities forced the permanent closure of underground mining operations in 1995.

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