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
1. Roughly spherical or ellipsoidal body, produced as a result of local early cementation within a sediment. It is often found with a fossil as a ‘nucleus’. The size ranges from approximately 1mm to more than 1 m, and concretions are generally monomineralic.

2. In pedology, the localized concentration of material, e.g. calcium carbonate or iron oxide, in the form of a nodule; such nodules are of various sizes, shapes, and colours.

con·cre·tion / kənˈkrēshən; kän-/ • n. a hard solid mass formed by the local accumulation of matter, esp. within the body or within a mass of sediment. ∎  the formation of such a mass. DERIVATIVES: con·cre·tion·ar·y / -shəˌnerē/ adj.

concretion (kŏn-kree-shŏn) n. a stony mass formed within such an organ as the kidney, especially the coating of an internal organ or a foreign body with calcium salts. See also calculus.

Concretion

a lump, nodule, or clot; a cohesion of particles.

Examples: concretion of ceremonial matters, 1634; of marine shells, 1796; of salt, 1697; of slime, 1626.

concretion A localized concentration of material (e.g. calcium carbonate or iron oxide) in the form of a nodule of varying size, shape, or colour.

concretion A localized concentration of material (e.g. calcium carbonate or iron oxide) in the form of a nodule of varying size, shape, or colour.

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electrocution, elocution, evolution, execution, institution, interlocution, irresolution, Lilliputian, locution, perlocution, persecution, pollution, prosecution, prostitution, restitution, retribution, Rosicrucian, solution, substitution, volution •cushion • resumption • München •pincushion •Belorussian, Prussian, Russian •abduction, conduction, construction, deduction, destruction, eduction, effluxion, induction, instruction, introduction, misconstruction, obstruction, production, reduction, ruction, seduction, suction, underproduction •avulsion, compulsion, convulsion, emulsion, expulsion, impulsion, propulsion, repulsion, revulsion •assumption, consumption, gumption, presumption •luncheon, scuncheon, truncheon •compunction, conjunction, dysfunction, expunction, function, junction, malfunction, multifunction, unction •abruption, corruption, disruption, eruption, interruption •T-junction • liposuction •animadversion, aspersion, assertion, aversion, Cistercian, coercion, conversion, desertion, disconcertion, dispersion, diversion, emersion, excursion, exertion, extroversion, immersion, incursion, insertion, interspersion, introversion, Persian, perversion, submersion, subversion, tertian, version •excerption