Rhodochrosite

specimen number:
2062233

location:
Chicagon Mine, Iron Co., Michigan, USA

description:
Rich pink masses of rhodochrosite throughout matrix. This has been cut and polished on one face to show the color.

The Chicagon mine, situated in Bates Township within Iron County, Michigan, was a notable underground iron ore operation located on the western end of the historic Menominee Iron Range. Geologically, the deposit is a Paleoproterozoic sedimentary iron-formation localized within the heavily folded and faulted Riverton Iron-Formation, which typically consists of interbedded chert, slaty iron carbonate, and secondary iron oxides. High-grade, merchantable ore bodies composed of soft red hematite and goethite were formed through supergene enrichment, where deep-circulating meteoric waters leached out silica along complex structural folds, leaving behind concentrated pockets that were locally associated with distinct manganese mineralization. Historically, formal exploration and underground development of the property were initiated in the early twentieth century, leading to steady production under the management of the Munro Iron Mining Company starting in 1909. The mine operated continuously for over a decade, shipping roughly 1.2 million tons of iron ore to Great Lakes ports before high operating costs and economic shifts led to the permanent cessation of all mining activities in 1922.

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