Manganite

specimen number:
2062127

location:
Jackson Mine, Negaunee, Marquette Co., Michigan, USA

description:
A spray of bright lustrous black crystallized manganite almost 2.0 cm across on matrix. Collected on May 11, 1998.

The Jackson Mine, located in Negaunee, Michigan, holds the distinction of being the first iron mine in the Lake Superior region, marking the birth of the massive Marquette Iron Range industry. Geologically, the deposit consisted of high-grade hematite and magnetite hosted within the Negaunee Iron Formation, a Precambrian sedimentary unit composed of alternating layers of iron oxides and chert (jasper). This formation was created through the chemical precipitation of iron in ancient oceans approximately two billion years ago. Historically, the deposit was first identified in 1845 with the help of Marji-Gesick, a local Ojibwa chief, who led explorers to a location where iron ore was exposed under the roots of a fallen pine tree. The Jackson Mining Company began formal operations in 1848 and continued production for several decades, eventually closing in 1924 as deeper and more efficient mines surpassed it. Today, the site is a National Historic Landmark and a public park, where the original open pits and tunnels serve as a memorial to the pioneers of American industrial mining.

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