concretion


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concretion,

mass or nodule of mineral matter, usually oval or nearly spherical in shape, and occurring in sedimentary rock. It is formed by the accumulation of mineral matter in the pore spaces of the sediment, usually around a fossil or fossil fragment acting as a nucleus. Most concretions are very dense and compact, and are usually composed of calcite, silica, or iron oxide. The material making up the concretion is believed to come from the surrounding rock, being redeposited around the nucleus. Concretions range in diameter from a fraction of an inch to many feet, although most are but a few inches in diameter. Perhaps the best known are the flint nodules found in chalk deposits such as those at Dover, England. Concretions having radiating cracks filled with mineral matter are called turtle stones, or septaria.

concretion

[kän′krē·shən]
(geology)
A hard, compact mass of mineral matter in the pores of sedimentary or fragmental volcanic rock; represents a concentration of a minor constituent of the enclosing rock or of cementing material.

concretion

1. any of various rounded or irregular mineral masses formed by chemical precipitation around a nucleus, such as a bone or shell, that is different in composition from the sedimentary rock that surrounds it
2. Pathol another word for calculus
References in periodicals archive ?
The specimen was collected in a calcareous sandstone concretion and consists of three vertebrae and 11 fragmentary gill rakers.
The fact that block B" was propped against a concretion about 100mm in height suggests that the latter, although modest in size, was already present.
say a poem should be concrete, prove concretion abstract: say a poem
I know how hard it is to build up from words alone the full concretion of an object.
Though this kind of holism represents a departure from Hegel's understanding of the concrete universal, there are important similarities between Hegel and the British Idealist in that both use the concrete universal to show that, as Greene puts it, the process of thought is one of concretion rather than abstraction.
After soaking the cannons to remove corrosive salts, lab workers began removing the concretion, eventually revealing the wood base and metal barrel of one of the cannons.
Some are surprised to learn that what they thought was an artifact is not, but instead a geological oddity, like a mineralized concretion.
Some of these methodologies can be considered of general application and, therefore, they lack of concretion and are vague, while others are for application in a low-level and their concretion is clearer.
Square, dead winter, with a wind, the concretion of the snow piled
This time-consuming conservation takes many steps and, therefore, it can be several months before an artifact is removed safely from a concretion.
Images were obtained by positioning the x-ray tube and panel on opposite sides of the concretion.