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 ?
Developing lithocytes are recognizable by their refractile concretions of various sizes, although cell boundaries are not discernible (Figs.
Some concretions constantly are sprayed with water to preserve the artifacts within; others rest inside water tanks.
In some cases, the original object decayed completely while the concretion that formed around it remained.
The intrinsic concretion of the idea constitutes its latent actuality, which necessarily becomes manifest in the finite and the temporal as the intelligible power of the self or as the powerful intelligibility of facts.
Murillo (1998) explains that some level of the unit was deposited in a shallow marine environment (foreshore) due to the presence of sedimentary concretions and hard grounds.
A wrought-iron kettle hanger, or handle, has been excavated from concretion.
Such views of concretion are distinct from the willful, vitalistic immediacy sometimes ascribed to Nietzsche.
A nodule or concretion is a hard "pocket" of soil cemented by iron or other substance.
Actually, the bezoar stone is found as a calculus or concretion in the stomachs or intestines of various ruminants, such as antelopes, camels, deer, and goats.
The third stage is treating this product, known as concretion, to separate the waxes and leave the absolute essential oil in a pure state.
3) If [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], then either E [assertion sign] m':Public or E [assertion sign] m:Secret, and there is a concretion A such that