Formula: Ca2(Mg,Fe)5Si8O22(OH)2 Monoclinic Description: Actinolite is a common member of the amphibole family. It typically forms during low-grade metamorphism of mafic igneous rocks (such as basalt and gabbro) or carbonate-rich rocks such as limey mudstones. ASHLAND COUNTY: Van …
Florence County
Allanite
Formula: (Ce,Ca,Ce,La,Nd,Y)2(Al,Fe)3(Si2O7)(SiO4)O(OH) Monoclinic Description:Allanite refers to a group of minerals found as an accessory in a number of different rocks such as syenite, granite and gneiss. It may also be a component of granite pegmatite. It …
Alluaudite
Formula: (Na,Ca)Mn2+(Mn,Fe3+,Fe2+,Mg)2(PO4)3 Monoclinic Description:This is a series of rare phosphate minerals found in granite pegmatites.FLORENCE COUNTY: Described as a component of tan to light brown phosphate nodules associated with apatite, heterosite-purpurite and schorl in the south end …
Almandine
Formula: Fe3Al2(SiO4)3 Isometric Description: Almandine is a common garnet found in a many metamorphic rocks such as schist, gneiss, amphibolite and iron formation. It is commonly associated with micaceous minerals such as muscovite, biotite and chlorite and …
Amblygonite
Formula: (Li,Na)Al(PO4)(F,OH) Triclinic Description: Amblygonite montebrasite pegmatite. From near Fern, Florence County, Wisconsin. (Photo by Al Falster.) Amblygonite is generally found as massive white cleavable masses in complex granite pegmatites. FLORENCE COUNTY: Amblygonite masses up to 5 …
Andalusite
Formula: Al2SiO5 Orthorhombic Description: Andalusite is found in phyllites, schists and gneisses and associated quartz veins. It indicates relatively low pressure metamorphism of aluminum-rich rocks, such as shales. ASHLAND COUNTY: Andalusite occurs as “chiastolite” in fine-grained schists outcropping …
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 …
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 …
Behierite
Formula: (Ta,Nb)BO4 Tetragonal Description:Behierite is an extremely rare mineral found in certain granitic pegmatites. FLORENCE COUNTY: Behierite occurs as “transparent colorless to white crystals” up to 400 microns across with quartz, elbaite, albite, manganotantalite, and manganoapatite in the …
Bermanite
Formula: Mn2+Mn3+2(PO4)2(OH)2.4H2O Monoclinic Description: Bermanite is a rare mineral formed in granitic pegmatites in association with other phosphate minerals. FLORENCE COUNTY: Subhedral tabular red crystals of bermanite less than 1.5 mm. in diameter are reported associated with …