Formula: PbSO4 Orthorhombic Description: Close-up of pale yellow anglesite crystals on galena. Largest crystal is about 2 mm across. Bear Hole Mine, Shullsburg, Lafayette County, Wisconsin. (Image courtesy of Tom Loomis, Dakota Matrix Minerals, Rapid City, South Dakota.) Anglesite is a …
Iowa County
Aragonite
Formula: CaCO3 Orthorhombic Description: Aragonite forms in low temperature hydrothermal deposits, especially as sinter around hot springs and amygdules in basalts. It also occurs as speleothems, as organic or inorganic precipitates in marine sediments. Finally, it forms …
Aurichalcite
Formula: (Zn,Cu)5(CO3)2(OH)6 Monoclinic Description: Aurichalcite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 082. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew …
Azurite
Formula: Cu3(CO3)2(OH)2 Monoclinic Description: Azurite is an attractive blue mineral found as a secondary weathering and supergene mineral formed from the alteration of native copper and other copper minerals. It is often found associated with and altering …
Baryte
Formula: BaSO4 Orthorhombic Description:Baryte is found general in low temperature hydrothermal deposits. It is most common in Wisconsin in the Upper Mississippi Valley zinc-lead district in Grant, Iowa, and Lafayette Counties where it is associated with …
Bornite
Formula: Cu5FeS4 Orthorhombic Description: Bornite forms as a primary hydrothermal precipitate or a later supergene replacement mineral. It occurs with other copper minerals such as covellite, malachite and azurite. It is marked by its intense purple to …
Calcite
Formula: CaCO3 HEXAGONAL Description: Calcite sceptor crystals from Shullsburg, Wisconsin. UW–River Falls specimen. Sample is about 8 cm high. (Photo by Pete Rodewald.) Calcite is an abundant mineral found in many geological environments. It forms by precipitation from …
Calcite Speleothems
Formula: CaCO3 HEXAGONAL Description: Speleothems are precipitates, usually made of calcite, in caverns. They should be conserved and not be collected from caves in order to preserve the caves’ beauty, interest and scientific values. CRAWFORD COUNTY: Abundant speleothems …
Celadonite
Formula: K(Mg,Fe)(Fe3+(Si4O10)(OH)2 Monoclinic Description: Celadonite is an earthy green to blue-green mineral formed by low grade hydrothermal of diagenetic alteration of other minerals or volcanic glass. GRANT COUNTY: Celadonite is reported from the Bridgeport Quarry, 3 miles SE …
Cerussite
Formula: PbCO3 Orthorhombic Description: Cerussite is formed by the alteration of galena in the presence of carbonate. Heyl et. al. (1959) describe it as a common mineral throughout the zinc-lead district, usually as massive gray to yellowish …