WGNHS
Wisconsin Geological and Natural History Survey

Corrensite

Green to white corrensite with chlorite in calcite, from the quarry west of Hurley in Iron County, Wisconsin.

Formula: (Mg,Fe)9 ((Si,Al)8O20)(OH)10.nH2O Orthorhombic

Description:

Pale green to cream corrensite, likely pseudomorphous after a zeolite-group mineral, with white calcite in cavity in basalt. From a rock quarry near Hurley, Iron County, Wisconsin. Edge of quarter for scale. (Photo by W. Cordua.)

Corrensite is a mineral formed from regular interlayers of chlorite with either vermiculite or smectite. It forms during low grade or hydrothermal metamorphism of basaltic rocks.

IRON COUNTY: Corrensite is found pseudomorphically replacing primary elongated crystals several cms. long of an unknown zeolite in amygdules in a basaltic rock in a quarry  west of Hurley, Wisconsin. Associated minerals are calcite, chlorite and  (Cordua, 2011).