Galena with Sphalerite

specimen number:
2062305

location:
Holyoke Mine, Marquette Co., Michigan, USA

description:
Right cleavages of galena throughout this quartz matrix with sphalerite. A good ore example for the locality. Collected in 1998.

The Holyoke mine, located northwest of Marquette in Marquette County, Michigan, was a historic underground exploration and mining venture targeted at silver and lead ores. Geologically, the site is situated within Precambrian metamorphic rocks of the Marquette Iron Range district, where localized hydrothermal veins deposited galena, sphalerite, and silver-bearing minerals within host schists and quartzites. Formal operations began around 1864 under the direction of the Holyoke Silver Mining Company, which excavated multiple shafts and an adit during the regional silver excitement of the mid-1860s. Despite substantial initial investment, including the installation of a stamp mill to process the ore, the veins proved to be narrow and economically non-viable. Commercial production ceased entirely around 1866 due to low ore grades and high operating costs.

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