Iron Ridge Mine, Iron Ridge Mines, Iron Ridge Mining District, Dodge County, Wisconsin, USA
42 mm. at longest point. Oolitic Hematite
Iron Ridge Mines, Iron Ridge Mining District, Dodge County, Wisconsin, USA
Hand sample of the oolitic hematite "soft ore" of the Ordovician Neda formation. Scale is in centimeters.
© William S. Cordua
Old postcard dated 1908.
The underground workings have been turned into a major haven for bats. The site is managed (2016) by the University of Wisconsin-Milwaukee, which does significant biological research there.
One of the few existing outcrops of the oolitic Neda Formation, southwest of the opening to the bat hibernaculum.