Formula: NiAs Hexagonal Description: Nickeline, also referred to as “niccolite”, is a rare mineral found in high temperature hydrothermal deposits, especially those in mafic igneous rocks. Other nickel minerals, pyrrhotite and chalcopyrite are commonly associated. ASHLAND …
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Almandine
Formula: Fe3Al2(SiO4)3 Isometric Description: Almandine is a common garnet found in a many metamorphic rocks such as schist, gneiss, amphibolite and iron formation. It is commonly associated with micaceous minerals such as muscovite, biotite and chlorite and …
Augite
Formula: (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 Monoclinic Description: Augite is the most common mineral in the pyroxene family. It has many varieties due to the variation in chemistry possible in its complex coupled solid solution series. Augite is common in gabbroic …
Epidote
Formula: Ca2(Al2Fe3+)(Si2O7)(SiO4)O(OH)2 Monoclinic Description: Epidote is a common mineral formed during low grades of metamorphism and hydrothermal activity. It is particular common in metamorphosed basalts and gabbros where it replaces plagioclase, pyroxene and olivine. It can also …
Hematite
Formula: Fe2O3 Hexagonal Description: “Needle Ore” hematite, longest needle is about 20 cm long. From Montreal Mine in Iron County, Wisconsin. (Photo by W. Cordua.) Hematite is an extremely common mineral. It can form as a sedimentary precipitate, …
Pipestone
Formula: Mixture of pyrophillite and sericite. Description:Pipestone is a compact pink to red metamorphosed mudstone (or argillite) of a consistency that allows it to be carved into pipes and other art objects. It is found as thin …
Plumbogummite
Formula: PbAl3(PO4)2(OH)5.H2O Hexagonal Description: Plumbogummite is a rare secondary mineral found in the oxidized zone over lead-bearing deposits. RUSK COUNTY: Plumbogummite occurs in the oxidized zone at the Flambeau Mine, near Ladysmith (Jones, Jones, and LaBerge, 1999). …
Staurolite
Formula: (Fe,Mg,Zn)2Al9(SiO4)4(OH,O)2 Monoclinic Description: Staurolite forms during the metamorphism of aluminous rocks at intermediate temperatures and pressures. It can form large euhedral crystals in schist, associated with muscovite, biotite, almandine and kyanite. Some crystals show distinctive cross …
Stibiotantalite
Formula: Sb(Ta, Nb)O4 Orthorhombic Description: Stibiotantalite is a rare mineral forming dark brown, yellow brown or reddish brown tabular crystals in complex granite pegmatites. FLORENCE COUNTY: Falster (1992, personal communication) reports stibiotantalite as occurring in the complex pegmatites …
Uraninite
Formula: UO2 Isometric Description: Uraninite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 1134. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew …