Formula: Fe1-xS Monoclinic Description: Pyrrhotite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 867. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by …
Oconto County
Quartz
Formula: SiO2 Hexagonal Description: Quartz is the most abundant mineral. It is an essential component of granitic igneous rocks, of sedimentary rocks such as sandstone and chert and of metamorphic rocks such as quartzites. It is a …
Scapolite Group
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 …
Sillimanite
Formula: Al2SiO5Orthorhombic Description: White elongated sillimanite crystals in schist with lustrous grey graphite, white quartz and pink garnet altering to iron oxide. Alder Gulch, near Virginia City, Montana. Field of view is about 0.5 cm left to right. (Photo …
Vesuvianite
Formula: (Ca,Na,vacancy)19(Al,Mg,Fe)13(vacancy,B,Al,Fe)5(Si2O7)4(SiO4)10(OH,F,O)10 Tetragonal Description:Vesuvianite most commonly forms in metamorphosed calc-silicate rocks.OCONTO COUNTY: Vesuvianite reportedly occurs with garnet, scapolite, clinopyroxene, hornblende and plagioclase in the Waupee Formation in the Mountain area. Here it is found as a contact metamorphic …