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  2. Concretion - Wikipedia

    en.wikipedia.org/wiki/Concretion

    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.

  3. Soil matrix - Wikipedia

    en.wikipedia.org/wiki/Soil_matrix

    The soil matrix is the solid phase of soils, and comprise the solid particles that make up soils.Soil particles can be classified by their chemical composition as well as their size.

  4. Wikipedia : Picture peer review/Sandstone concretion

    en.wikipedia.org/.../Sandstone_concretion

    A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity (i.e. the spaces between the sediment grains). The image shows a Sandstone Concretion in the wall at the beach of Año Nuevo State Reserve. This concretion was too high in the wall to place a ruler, but I estimate it to be about 400 mm long.

  5. Kettle Point Formation - Wikipedia

    en.wikipedia.org/wiki/Kettle_Point_Formation

    These concretions lack any obvious nuclei, such as macrofossils, at their centers. These concretions occur in the black shale in the lower part of the Kettle Point Formation. Because the concretions are so much harder than the enclosing weakly indurated shale, they readily weather out of the shale along the shoreline and are incorporated into ...

  6. Nodule (geology) - Wikipedia

    en.wikipedia.org/wiki/Nodule_(geology)

    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.

  7. Enterolith - Wikipedia

    en.wikipedia.org/wiki/Enterolith

    An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting. If there is evidence of complications, they must be removed.

  8. Mazon Creek fossil beds - Wikipedia

    en.wikipedia.org/wiki/Mazon_Creek_fossil_beds

    The fossiliferous concretions are found in the Mazon River area of Grundy, Will, Kankakee, and Livingston counties. Additional fossils are found in LaSalle County, Illinois; between the Vermilion River and Marseilles, Illinois. The ironstone concretions are recovered from exposures along streams, roadcuts and in active or abandoned coal mine areas.

  9. Coal ball - Wikipedia

    en.wikipedia.org/wiki/Coal_ball

    A coal ball is a type of concretion, varying in shape from an imperfect sphere to a flat-lying, irregular slab.Coal balls were formed in Carboniferous Period swamps and mires, when peat was prevented from being turned into coal by the high amount of calcite surrounding the peat; the calcite caused it to be turned into stone instead.