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The concretions were created by the precipitation of iron, which was dissolved in groundwater. The iron was originally present as a thin film of iron oxide surrounding sand grains in the Navajo Sandstone. Groundwater containing methane or petroleum from underlying rock beds reacted with the iron oxide, converting it to soluble reduced iron ...
Similar to the marine nodules, concretion layers are defined based on iron and manganese content as well as their combination. [2] High iron content nodules appear a red or brown color, while high manganese content appears black or grey. [2] The dominant metal oxide is related to the elements enriched in the nodule.
This boulder of ferricrete near Questa, New Mexico, is an iron oxide-cemented colluvial breccia. Ferricrete deposits along the Animas River watershed in Colorado have been classified as: alluvial iron oxyhydroxide-cemented conglomerates along old stream channels; colluvial iron oxyhydroxide-cemented, poorly sorted breccias with massive to minor ...
Iron formations can be divided into subdivisions known as: banded iron formations (BIFs) and granular iron formations (GIFs). [ 3 ] The above classification scheme is the most commonly used and accepted, though sometimes an older system is used which divides iron-rich sedimentary rocks into three categories: bog iron deposits , ironstones , and ...
Ironstone (sandstone with iron oxides) from the Mississippian Breathitt Formation, Mile Marker 166, I-64, Kentucky. Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron ore compound from which iron (Fe) can be smelted commercially.
Iron oxides feature as ferrous or ferric or both. They adopt octahedral or tetrahedral coordination geometry. Only a few oxides are significant at the earth's surface, particularly wüstite, magnetite, and hematite. Oxides of Fe II. FeO: iron(II) oxide, wüstite; Mixed oxides of Fe II and Fe III. Fe 3 O 4: Iron(II,III) oxide, magnetite; Fe 4 O ...
They described it as a dark-gray shale, fossiliferous, with veins and seams of gypsum, and concretions of iron oxide. The Pierre Shale is about 3,138 feet (956m) thick at the type locality. It overlies the Niobrara division and underlies the Fox Hills beds. [1] It was named for an occurrence near Fort Pierre on the Missouri River in South ...
Although channel iron deposits are typically low-grade at 53% to 57% Fe in-situ, they are composed of goethite-limonite which are hydrated iron oxide species. Ore typically contains around 8% to 12% water, and <5% SiO 2, and <3% Al 2 O 3. The hydrous iron oxides can be calcined, and the CID ore on a volatile-free basis is around 63% Fe or more.