Siderite is also the name of a type of iron meteorite.Siderite is a mineral composed of iron(II) carbonate (FeCO3). It takes its name from the Greek word σίδηρος sideros, "iron". It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Zinc, magnesium and manganese commonly substitute for the iron resulting in the siderite-smithsonite, siderite-magnesite and siderite-rhodochrosite solid solution series.
Concretions vary considerably in their compositions, shapes, sizes and modes of origin. Septarian concretions or septarian nodules, are concretions containing angular cavities or cracks, called "septaria". The word comes from the Latinword septum; "partition", and refers to the cracks/separations in this kind of rock. Some websites incorrectly derive the term from the Latin word septem, meaning "seven". Cracks are highly variable in shape and volume, as well as the degree of shrinkage they indica
The Gammon member of the Pierre shale of the northern Great Plains, USA, contains abundant siderite concretions. The relative depth and time of siderite precipitation can be inferred from the structure, mineralogy and isotopic composition of these concretions. Concretions that formed at shallow depths, early in the history of the sediment, contain a high percentage (75-85%) of carbonate
concretions in the aeolian Navajo Sandstone of Utah. In all three deposits, rinded concretions formed when pre-existing, siderite-cemented concretions were oxidized within a sand matrix. Unlike ﬂuvial examples, siderite in the Navajo Sandstone was autochthonous and of late diagenetic origin, having
Concretions Composed of a carbonate mineral such as calcite. A concretion is a compact mass of mineral matter, usually spherical or disk-shaped, embedded in a host rock of a different composition.
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(c) Hypothesized sequence of events required for preservation in siderite concretions. (i) After rapid burial, decay of the organisms creates a geochemical microenvironment around the carcass and depletes interstitial sulphate. (ii) Siderite precipitation creates a ‘proto-concretion’ that acts to entomb the organism and resists compaction.
North Dakota, especially in the wondrously sculpted badland areas of the west, has a fantastic variety of concretions and nodules. Some are the size and shape of petrified logs, while others, perched atop pedestals of softer sediments that they shield from erosion, have lens or disk shapes.
Calcite Group. Magnesite-Siderite Series, Rhodochrosite-Siderite Series, Siderite-Smithsonite Series. Crystals typically found as brown to tan rhombohedrons in clusters, faces often curved or composites; more often found as medium to dark brown massive fine-grained material or as massive crystalline material with exposed curved cleavage surfaces.
The Upper Cretaceous Gammon Shale in the northern Great Plains contains abundant siderite concretions that formed during the early compactional history of the fine-grained, marine sediments. The relative depth of siderite precipitation can be estimated on the basis of textural, mineralogical, and isotopic evidence.
Most fossils are found in concretions (siderite nodules) along the Mazon River area of the Illinois counties of Grundy, Will, Kankakee, Livingston and LaSalle, and are recovered from formation exposures along the river and nearby streams, roadcuts and within waste piles of abandoned and active coal mines.
The siderite concretions occur only in the lower 3–5 m (c. 10–15 ft) of the member, and only where the shale is more than 15 m (c. 50 ft) thick. The shale is coarser and bears sandstones near its top. The Mecca Quarry Shale is a typical Pennsylvanian black shale,
Oct 01, 2013· The occurrence of abundant siderite concretions in association with crinoid-bearing horizons provided an opportunity to examine the relationships between fossil preservation and concretion morphology and character. Siderite concretions are
The proto-concretion was cemented prior to compaction of the sediments by siderite as a result of methanogenic production of (13) C-rich bicarbonate-which varies both between Essex and Braidwood concretions and between fossiliferous and unfossiliferous concretions.
Shale; brownish black to greenish gray, weathers brown; carbonaceous to clayey, laminated to thin bedded, fissile parting; carbonate and/or siderite concretions in lowermost 50 feet; petroliferous odor; 250 to 500+ feet thick. Includes Olentangy Shale south of central Delaware Co.
When the ammonites died, their shells fell to the bottom of the seaway and were covered with sediment. Many of them served as a nucleus for the formation of siderite concretions which are now found in the Bearpaw Formation. The ammonite fossils within these concretions sometimes have an outer shell layer composed of gem-quality Ammolite.
Other typical habits include the scalahedron, crusts, sphericules, concretions and complicated botyroidal masses. Siderite forms mostly in sedimentary and hydrothermal environments, although it is also found in some igneous pegmatites. Siderite is a common mineral although excellent, attractive crystal specimens are sometimes hard to find.
One of the best records of late Paleozoic ecosystems, the Mazon Creek Lagerstätte is world famous for its striking flora and fauna preserved within siderite concretions. Distinct from other late Carboniferous concretionary Lagerstätten because of the remarkable fidelity of soft tissues and pigments that are frequently preserved, the Mazon Creek has seen a revival in investigations during the
A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil.Septarian concretions are concretions containing angular cavities or cracks, called "septaria". The septaria are the calcite filled cracks at the centre of the rock, indicating where the centres of the concretions have shrunk
MAZON CREEK FOSSILS THE OCCURRENCE AND ORIGIN OF SIDERITE CONCRETIONS IN THE FRANCIS CREEK SHALE (PENNSYLVANIAN) OF NORTHEASTERN ILLINOIS Bertram G. Woodland Curator of Petrology Field Museum of Natural History Chicago, Illinois Richard C. Stenstrom Department of Geology Beloit College Beloit, Wisconsin ABSTRACT Siderite concretions are well known from
The concretions are composed of 50-100 mu m, zoned crystallites, which exhibit no noticeable center-to-edge variation within any individual concretion. This indicates that siderite crystallites
Sep 15, 2015· Carbonate concretions occur in sedimentary rocks of widely varying geological ages throughout the world. Many of these concretions are isolated spheres, centered on fossils. The formation of such
Examples of how to use “concretion” in a sentence from the Cambridge Dictionary Labs. Cambridge Dictionary +Plus; My profile +Plus help; Log out; Dictionary . Definitions. Clear explanations of natural written and spoken English The member consists of coals, claystones and siltstones rich in siderite concretions, and three to four
Mar 12, 2014· The Lawrence Formation near Lawrence, Kansas has produced siderite concretions containing horseshoe crabs and spiders, at least. I have not had the pleasure of finding any myself, though. Also, would you include the arthropod-bearing concretions from the UK?
Jan 05, 2014· The decay of their soft parts produced hydrogen sulfide gas ad carbon dioxide, triggering the geochemistry that caused the precipitation of siderite around them. The hard concretion that resulted was likely in a matrix of soft shale. The strength of the siderite kept the fossils from being crushed by the weight of sediment above.
Apr 08, 2013· Concretions formed as the sediment grains were cemented around some nucleus, such as a fossil (but not always). They form by various means. In the case of some fossils in ironstone concretions, CO2 produced by initial decomposition combined with iron in the groundwater to form iron carbonate (i.e. siderite).
Fossiliferous concretion from the Meadville Shale Member of the Cuyahoga Formation (Lower Carboniferous) exposed near Wooster, Ohio. Fossiliferous siderite concretion from the Lower Carboniferous. Sand from the beach at Scala dei Turchi, Sicily.
Siderite concretion horizons are known both from the paralic and terrestrial sediments of the Upper Silesian Basin. Significant horizon above the No. 22 Coal Seam in the Upper Suchá Member of Karviná Fm. (Westphalian, Pennsylvanian) was investigated by
Examples of how to use “siderite” in a sentence from the Cambridge Dictionary Labs. Cambridge Dictionary Plus; My profile; How to Log out; Dictionary . Definitions. Clear explanations of natural written and spoken English The member consists of coals, claystones and siltstones rich in siderite concretions
The proto-concretion was cemented prior to compaction of the sediments by siderite as a result of methanogenic production of (13) C-rich bicarbonate-which varies both between Essex and Braidwood
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