Formula: Varies Description: Mifflin L5 chondrite meteorite fragment showing internal brecciation. (Image courtesy John Valley; unauthorized reproduction is prohibited.) CLARK COUNTY: Two stony meteorites with a combined weight of over 200 pounds fell at 6:15 P.M. on …
Iowa County
Millerite
Formula: NiS Hexagonal Description: Millerite is a low temperature hydrothermal mineral found in vugs in carbonate rocks and as an alteration product of other nickel minerals. Millerite typically forms long brassy fibers making very aesthetic specimens. …
Minium
Formula: Pb3O4 Tetragonal Description: Minium is a rare mineral found as red dull to greasy masses in the oxidized zone of lead deposits where it forms as the result of the alteration of galena. IOWA COUNTY: Minium is …
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 …
Psilomelane
Formula: Mixture of hydrate manganese-barium oxides Description: Psilomelane is used as a blanket term to denote a variety of hard massive mixtures of manganese oxides. Most, but not all, psilomelane is the mineral romanechite (BaMn2+Mn4+8O16(OH)4 ). The …
Pyrite
Pyrite is the most common sulfide found in many environments. It is a common accessory mineral in igneous, sedimentary and metamorphic rocks. It also is abundant in most hydrothermal deposits. Only the most significant occurrences …
Pyrolusite
Formula: MnO2 Tetragonal Description: Pyrolusite forms as a weathering product of other manganese minerals, as concretions or dendrites deposited by ground water or as nodules precipitated from lake water. Pyrolusite is often soft and soils the fingers, …
Pyromorphite
Formula: Pb5(PO4)3Cl Hexagonal Description: Pyromorphite. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 861. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.) Pyromorphite is …
Pyrrhotite
Formula: Fe1-xS Monoclinic Description: Pyrrhotite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 867. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by …
Quartz
Formula: SiO2 Hexagonal Description: Quartz is the most abundant mineral. It is an essential component of granitic igneous rocks, of sedimentary rocks such as sandstone and chert and of metamorphic rocks such as quartzites. It is a …