Formula: K(Li,Al)2(Si,Al)4O10(F,OH)2 Monoclinic Description: Lepidolite is a relative of muscovite, forming pink, purple or yellow flakes or scaly crystals in lithium-rich granite pegmatites. Lepidolite (pink) showing “line-rock texture” from near Fern, Florence County, Wisconsin. (Photo by Al Falster.) …
Florence County
Limonite
Formula: Mixture of hydrated iron oxides Description: Limonite is a general term for a mixture of fine-grained iron oxides, generally dominated by goethite, but also possibly containing hematite, lepidochrocite and other minerals. It forms from the …
Lithiophilite
Formula: LiMnPO4 Orthorhombic Description: Lithiophilite forms reddish to yellowish masses, often oxidized dark brown to black in granite pegmatites. It is often associated with a host of other rare phosphate minerals. FLORENCE COUNTY: Lithiophilite occurs in the …
Magnetite
Formula: Fe2+Fe3+2O4 Isometric Description: Magnetite is a common mineral found at many localities in Wisconsin. Only localities that where the mineral is present in great abundance or as unusual material are listed here. Magnetite occurs as an …
Microlite
Formula: (Na,Ca)2Ta2O6(O,OH,F) Isometric Description: Microlite refers to a group of rare minerals related to pyrochlore that form equant to irregular pale yellow, brown, red or green grains in complex granite pegmatites. FLORENCE COUNTY: Microlite occurs with lepidolite …
Molybdenite
Formula: MoS2 Hexagonal Description: Molybdenite is a relatively common hydrothermal mineral. It is most often found in vein complexes associated with granitic igneous rocks and related skarns that form at medium to high temperatures. It is economically …
Monazite
Formula: (Ce,La,Nd,Th)PO4 Monoclinic Description: Monazite refers to a group of minerals dominated by various rare earth elements. These minerals commonly form reddish brown to yellowish tabular crystals and granular masses in granitic rocks and placer deposits derived …
Muscovite
Formula: KAl2(AlSi3)O10(OH,F)2 Monoclinic Description:Muscovite is a common mica, forming silvery to pale-colored flakes most commonly schists and granite pegmatites. It can survive weathering, and form sparkling grains in sands and sandstone. Muscovite. From the mineral collection of …
Opal
Formula: SiO2.nH2O Amorphous Description: Opal is a mineraloid composed of spherical silica aggregates with various amounts of interstitial water. It forms under a wide range of low-temperature geological conditions. Opal may be deposited by silica secreting …
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 …