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Some of the most unusual concretion nuclei are World War II military shells, bombs, and shrapnel, which are found inside siderite concretions found in an English coastal salt marsh. [10] Depending on the environmental conditions present at the time of their formation, concretions can be created by either concentric or pervasive growth.
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.
Iron oxide copper gold (IOCG) deposits are considered to be metasomatic expressions of large crustal-scale alteration events driven by intrusive activity. The deposit type was first recognised by discovery and study of the supergiant Olympic Dam copper-gold-uranium deposit (Olympic Dam mine), and South American examples.
Iron ores are overwhelmingly derived from ancient sediments known as banded iron formations (BIFs). These sediments are composed of iron oxide minerals deposited on the sea floor. Particular environmental conditions are needed to transport enough iron in sea water to form these deposits, such as acidic and oxygen-poor atmospheres within the ...
The iron forming these concretions came from the breakdown of iron-bearing silicate minerals by weathering to form iron oxide coatings on other grains. During later diagenesis of the Navajo Sandstone while deeply buried, reducing fluids, likely hydrocarbons, dissolved these coatings.
The Pierre Shale is the host formation for commercial petroleum deposits in the Florence and Canon City fields in Fremont County, Colorado, and the Boulder Oil Field in Boulder County, Colorado. More recently, natural gas has been extracted in the Raton Basin in southern Colorado .
While, for the large majority of the allowable compositions, the iron oxide contents in the spherules were between 85 wt% and 96 wt%; further, the nickel content was always close to 0.3 wt%, a group of five standard oxides (MgO, Na 2 O, P 2 O 5, SO 3, and Cl) each had content above trace-level with a combined group content of 6.8 +/- 2.4 wt ...
Iron is stored in many organisms in the form of ferritin, which is a ferrous oxide encased in a solubilizing protein sheath. [ 10 ] Species of bacteria , including Shewanella oneidensis , Geobacter sulfurreducens and Geobacter metallireducens , use iron oxides as terminal electron acceptors .