Goethite

specimen number:
2062135

location:
Lake Superior Mine, Ishpeming, Marquette Co., Michigan, USA

description:
Fine example of lustrous botryoidal goethite. The sort of material was often referred to as grape ore. In good condition, at one time the specimen was part of the collection at the A. E. Seaman mineral Museum at Michigan Tech University.

The Lake Superior Mine, located in Ishpeming within the Marquette Iron Range of Michigan, was one of the most significant and long-lived iron ore operations in the region. Geologically, the mine targeted the Negaunee Iron Formation, a massive Precambrian unit consisting of alternating bands of specular hematite, magnetite, and red jasper. The ore bodies at this location were particularly noted for their high purity and structural complexity, often occurring in deep folds and troughs within the surrounding metamorphic rock. Historically, the Lake Superior Iron Company was organized in 1853, and the mine began regular shipments in 1858. It quickly became a cornerstone of the regional economy, utilizing both open-pit and underground mining techniques to extract millions of tons of ore. The mine remained a steady producer for nearly a century, with operations continuing under various owners, including the Oliver Iron Mining Company, until its eventual closure around 1948. Today, the legacy of the Lake Superior Mine is preserved through the massive "caving grounds" and historic structures that remain a prominent part of the Ishpeming landscape.

The A.E. Seaman Mineral Museum, located at Michigan Technological University in Houghton, serves as the official Mineral Museum of Michigan and holds one of the finest mineral collections in North America. Historically, the museum began as a teaching collection in 1902 and was named in honor of Professor Arthur Edmund Seaman, who served as its first curator and was instrumental in its early growth. The museum's primary mission is to preserve and display the mineral heritage of the Great Lakes region, with a world-class emphasis on the native copper deposits of the Keweenaw Peninsula and the iron formations of the Marquette Range. Over its century-long history, the museum has occupied several locations on campus, moving to its current award-winning facility near the university's south entrance in 2011. Today, it houses over 40,000 specimens and attracts thousands of visitors annually, acting as a vital educational resource for students and a premier destination for mineral enthusiasts worldwide.

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