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A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. [1] Concretions are often ovoid or spherical in shape, although irregular shapes also occur.
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.
Conjunctival concretions are generally asymptomatic.Common symptoms include eye discomfort, eye irritation, and foreign body sensation. Sometimes, the larger, harder or multiple concretions make the rubbing off of the superficial layers of the conjunctiva or eyelids to cause conjunctival abrasion, especially prominent when blinking.
The concretion in the nominated image looks as a bone. The image was created by mbz1. It appears in Concretions. I've nominated the image because IMO the facinating shapes of concretions, which made people from the 18th century wonder about them are still as mysterious now as they were then. IMO the image is a hiqh quality image with big ...
Devonian nodular limestone Concretionary nodular limestone at Jinshitan Coastal National Geopark, Dalian, China. In geology and particularly in sedimentology, a nodule is a small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition from the enclosing sediment or sedimentary rock.
It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions, which can encase three-dimensionally preserved fossils. [6] In sedimentary rocks, siderite commonly forms at shallow burial depths and its elemental composition is often related to the depositional environment of the enclosing sediments. [7]
These concretions occur as both spherical cannonball concretions and flat, disk-shaped or oval concretions. Unlike the Moeraki boulders, some of these concretions contain the bones of mosasaurs and plesiosaurs. [3] Similar large spherical concretions have been found in many other countries. [citation needed]
In the prostate gland, where they are also known as prostatic concretions, corpora amylacea are rich in aggregated protein that has many of the features of amyloid, whereas those in the central nervous system are generally smaller and do not contain amyloid. [3]