Formula: Na4Al3Si9O24Cl – Ca4Al6Si6O24(CO3) Tetragonal Description: Scapolite is a group of minerals related by complex solid solution substitutions. They are found in a wide range of metamorphic rocks formed both by regional and contact metamorphism. The …
Oneida County
Silver
Formula: Ag Isometric Description:Native silver is found in hydrothermal veins or, more rarely, as a supergene mineral. It is associated with gold, and a variety of sulfides such as galena, pyrite and acanthite. Major silver mineralization …
Sphalerite
Formula: ZnS Isometric Description: Banded sphalerite, near Hazel Green in Lafayette County, Wisconsin. Sample is about 1 cm long. Sphalerite occurs in a wide range of hydrothermal environments. It is common with chalcopyrite in exhalative massive …
Stilpnomelane
Formula: (K,Ca,Na)(Fe, Mg,Al)8(Si,Al)12(O,OH)36.nH2O Triclinic Description: Stilpnomelane is a brown micaceous to velvety to fibrous mineral found in various metamorphic rocks, especially those rich in iron. It often occurs with chlorite, epidote, magnetite, hematite and goethite and …
Talc
Formula: Mg3Si4O10(OH)2 Triclinic Description: Talc with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 1073. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew …
Tetrahedrite-tennantite
Formula: (Cu,Fe,Ag,Zn)12(Sb,As)4S13 Isometric Description:Tetrahedrite forms a solid solution series with tennantite and freibergite in moderate to low temperature hydrothermal deposits.DOUGLAS COUNTY: Irving (1882) reports finding tetrahedrite in “small quantities in traverse veins in copper-bearing rocks”. This occurrence has …
Tremolite
Formula: Ca2Mg5Si8O22(OH)2 Monoclinic Description: Tremolite marble from Florence County, Wisconsin. Field of view 7 cm across. (Photo by Al Falster.) Tremolite is formed by the metamorphism of calcium-rich rocks such as limestone and dolostone. It occurs in numerous …