Description: Massive to botryoidal smithsonite of a form originally called “dry bone ore” by miners. This was a major zinc ore in the mines of southwestern Wisconsin. From the Little Giant Mine, near Shullsburg, Lafayette …
Winnebago County
Meteorites
Formula: Varies Description: Mifflin L5 chondrite meteorite fragment showing internal brecciation. (Image courtesy John Valley; unauthorized reproduction is prohibited.) CLARK COUNTY: Two stony meteorites with a combined weight of over 200 pounds fell at 6:15 P.M. on …
Hemimorphite
Formula: Zn4Si2O7(OH)2.H2O Orthorhombic Description: Hemimorphite forms from the breakdown of sphalerite and other zinc minerals. It is common in the oxidized and supergene zones over hydrothermal deposits, where it is associated with smithsonite. Heyl et al. (1959) …
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 …
Pyrite
Pyrite is the most common sulfide found in many environments. It is a common accessory mineral in igneous, sedimentary and metamorphic rocks. It also is abundant in most hydrothermal deposits. Only the most significant occurrences …
Covellite
Formula: CuS Hexagonal Description: Covellite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 430. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by …
Fluorite
Formula: CaF2 Isometric Description: Fluorite crystals, from Sturgeon Bay in Door County, Wisconsin. Field of view is about 4 cm. (Photo by W. Cordua) Fluorite often forms coarse cleavable masses or cubic crystals. It can take on a …
Dolomite
Formula: CaMg(CO3)2 Hexagonal Description: Dolomite forms the main mineral in the bluff-forming rocks along the Mississippi River, such as Granddad Bluff near La Crosse. (Photo by W. Cordua) Dolomite is an abundant mineral in Wisconsin. It is a …
Marcasite
Formula: FeS2 Orthorhombic Description: Marcasite helectite, New Diggings area, Lafayette County, Wisconsin. Sample is about 8 cm long. (Photo by W. Cordua.) Marcasite is common in Wisconsin, often found in well-formed crystals in cavities and veins in the …
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 …