Formula: Y2Fe2+Be2Si2O10 Monoclinic Description: Gadolinite-(Y) is an extremely rare mineral found in certain complex granitic pegmatites. SHAWANO COUNTY: Black to dark green anhedral masses of gadolinite up to several cm. in diameter are found in the complex pegmatite …
Waupaca County
Plagioclase
Formula: CaAl2Si2O8 Triclinic Description: Plagioclase is a family of feldspar minerals forming a solid solution that ranges, relatively continuously, from pure sodium aluminum silicate (the end member called albite) to pure calcium aluminum silicate (the end member …
Goethite
Formula: FeO(OH) Orthorhombic Description: Stalactitic goethite from Montreal Mine in Iron County, Wisconsin. (Photo by W. Cordua.) Goethite is a common iron mineral. It often forms by weathering of other iron-rich minerals, thus is a common component …
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 …
Zircon
Formula: ZrSiO4 Tetragonal Description: Zircon in tabular crystal from the Nine Mile Pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.) Zircon is a common accessory mineral found in many different …
Bastnaesite Series
Formula: (Ce, La,Y, Nd)(CO3)F Hexagonal Description: Bastnaesite in platey crystals from the Nine Mile pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.) The bastnaesite series is a group of minerals …
Apatite Group
Formula: Ca5(PO4)3(F,Cl,OH) Hexagonal Description:Apatite denotes a family of minerals referred to variously in older literature as “fluorapatite,” “chlorapatite,” “carbonate-apatite” or “hydroxlyapatite” and in newer literature as apatite- (CaF) etc. depending on which anion group dominates. Members …