WGNHS
Wisconsin Geological and Natural History Survey

Pyromorphite

Pyromorphite. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 860. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.)

Formula: Pb5(PO4)3Cl Hexagonal

Description:

Pyromorphite. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 861. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.)

Pyromorphite is a rare mineral formed by the alteration of primary lead minerals in an oxidized zone or supergene zone environment.

IOWA COUNTY: Heyl et al. (1959) report pyromorphite as a rare secondary mineral in the Upper Mississippi Valley zinc-lead district in southwestern Wisconsin. A specific occurrence mentioned is the Eberle Mine, 5 miles north of Cobb (NW NW sec. 2 T.6N. R.1E.). Here it occurs as “pale green, yellow or brown hexagonal barrel-shaped crystals” associated with pyrite, chalcopyrite, aurichalcite, smithsonite, azurite, malachite and tenorite.