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 …
Marathon County
Arfvedsonite
Formula: Na3(Fe2+4Fe)Si8O22(OH)2 Monoclinic Description: Arfvedsonite is a member of the amphibole group usually found in low silica but highly alkaline igneous rocks such as nepheline syenites. It may be mistaken for hornblende, but is distinguished by its …
Arsenopyrite
Formula: FeAsS Monoclinic Description: Arsenopyrite is formed in hydrothermal deposits, especially those formed at medium to high temperatures. It is often associated with other sulfides such as pyrite and chalcopyrite. CLARK COUNTY: Reported from an unspecified locality …
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 …
Baddeleyite
Formula: ZrO2 Monoclinic Description: Baddeleyite is a rare zirconium oxide found in a variety of environments, including kimberlite, syenite and gabbro. It may survive weathering as a detrital mineral. KENOSHA COUNTY: Baddeleyite occurs as coatings on zircon from …
Baryte
Formula: BaSO4 Orthorhombic Description:Baryte is found general in low temperature hydrothermal deposits. It is most common in Wisconsin in the Upper Mississippi Valley zinc-lead district in Grant, Iowa, and Lafayette Counties where it is associated with …
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 …
Bavenite
Formula: Ca4Be2Al2Si9O26(OH)2 Orthorhombic Description: Bavenite is a rare mineral found in beryllium-rich granite pegmatites. MARATHON COUNTY: Forms white to gray bladed to acicular crystals up to 1 cm. in diameter in quartz-bearing pockets in pegmatites of the Wausau …
Bertrandite
Formula: Be4Si2O7(OH)2 Orthorhombic Description: Bertrandite twin, Nine Mile pluton, near Wausau, Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.) Bertrandite is a rare mineral found in beryllium rich pegmatites and hydrothermal veins. MARATHON COUNTY: Relatively common …
Beryl
Formula: Be3Al2Si6O18 Hexagonal Description: Beryl variety aquamarine from the Nine Mile pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. Field of view 2 cm. (Photo by Al Falster.) Beryl is most frequently found in granite …