Formula: Zn5(CO3)2(OH)6 Monoclinic
Description: Hydrozincite forms white earthy massive to reniform to stalactitic growths due to the alteration of sphalerite and other zinc minerals by ground water. It is likely quite common (but not often reported) in the weathering zone over the many zinc deposits in the Upper Mississippi Valley zinc-lead district in southwestern Wisconsin.
GRANT COUNTY: White crusts of platy hydrozincite crystals occur at a prospect 1.5 miles east of Tennyson, where it is admixed with smithsonite, hemimorphite and calcite (Heyl et al., 1959).
IOWA COUNTY: White botryoidal material, likely hydrozincite, occurs at Highland (Hobbs, 1905). It is also reported as finely fibrous to pearly porcellaneous coatings on smithsonite from the mines at Linden and Mineral Point. (Heyl, et al., 1959, Raasch, 1924, Irving, 1883, Strong, 1877).
— Occurs as chalky crusts on sphalerite on dumps of the Coker #1 mine. The crusts fluoresce blue under ultraviolet light.
LAFAYETTE COUNTY: Reported as a component of “drybone ore” in the Belmont and Calamine Quadrangles (Klemic and West, 1964).