Formula: CaTiSiO5 Monoclinic Description:Titanite is a common accessory mineral usually found as tiny grains in many different rocks. It is common in plutonic igneous rocks such as granite, diorite and syenite. Titanite also is a common accessory …
Marathon County
Topaz
Formula: Al2(SiO4)(F,OH)2 Orthorhombic Description: Topaz from the Nine Mile Pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.) Topaz forms in granitic pegmatites, in cavities in rhyolitic volcanic rocks and in residual …
Tourmaline Group
Formula: Na(Al,Fe,Li,Mg,Mn)3(Al,Cr,V,Fe)6(BO3)3Si6O18(O,OH,F)4 Hexagonal Description: Tourmaline var elbaite Animikie Red Ace pegmatite (red) showing comb texture in pegmatite wall zone. With altered Cs-beryl (yellow-green). Near Fern, Florence County, Wisconsin. (Photo by Al Falster.) Tourmaline is a complex group of …
Uranophane
Formula: Ca(UO2)2(HSiO4).5H2O Monoclinic Description: Uranophane and petrified wood from Henry Mountains, Utah. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 1147. Courtesy of the U.S. Geological Survey Denver Library Photographic …
Wollastonite
Wollastonite forms in highly metamorphosed marbles or calc-silicate rocks. IRON COUNTY: Wollastonite occurs as a fine-grained mix of intergrown fibers in an algal limestone deposited between basaltic lava flows. in outcrops northwest of Upson Lake. The …
Xenotime-(Y)
Formula: YPO4 Tetragonal Description: Xenotime-(Y) from the Nine Mile Pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.) Xenotime-(Y) is a rare accessory mineral generally found in complex pegmatites. It resembles zircon …
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 …
Zoisite
Formula: (Th,U)SiO4 Tetragonal Description: Thorite is a rare mineral found in pegmatites and hydrothermal deposits. Zoisite is formed in rocks subjected to low to medium grade metamorphism. If often results from the deterioration of plagioclase. It is …