Peloids

 Peloids are allochems that are composed of micrite, irrespective of size, shape, or origin. The two primary types of peloids are pellets and intraclasts. Another type of peloid is pseudo-oolith.[1][2][3]

Pellets (a type of peloid) and a brachiopod shell visible in a limestone thin-section; Bird Spring Formation (Carboniferous) of southern Nevada.

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Chert

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  Chert   (   / ˈ tʃ ɜːr t / ) is a hard, fine-grained   sedimentary rock   composed of   microcrystalline   (or   cryptocrystalline ) crystals of   quartz , [1]   the mineral form of   silicon dioxide   (SiO 2 ). [2]   Chert is characteristically of biological origin but may also occur inorganically as a chemical precipitate or a   diagenetic   replacement, as in   petrified wood . [3] Chert Sedimentary rock Chert Chert is typically composed of the petrified remains of  siliceous ooze , the biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of  diatoms , silicoflagellates, and  radiolarians . [4]   Precambrian  cherts are notable for the presence of fossil  cyanobacteria . [5]  In addition to  microfossils , [4]  chert occasionally contains  macrofossils . [6] [7]  However, some chert is de...
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Argillite

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  Argillite   (   / ˈ ɑːr dʒ ɪ l aɪ t / ) is a fine-grained   sedimentary rock   composed predominantly of   indurated   clay   particles. Argillaceous rocks are basically   lithified   muds and   oozes . They contain variable amounts of   silt -sized particles. The argillites grade into   shale   when the   fissile   layering typical of shale is developed. Another name for poorly lithified argillites is   mudstone . [ citation needed ]   These rocks, although variable in composition, are typically high in   aluminium   and   silica   with variable   alkali   and   alkaline earth   cations . The term   pelitic  or  pelite   is often applied to these   sediments   and rocks.   Metamorphism   of argillites produces   slate ,   phyllite , and pelitic   schist . Argillite Sedimentary rock A piece of black arg...
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Folk classification

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  The   Folk classification   is a technical descriptive classification of   sedimentary rocks   devised by   Robert L. Folk , an influential sedimentary   petrologist   and Professor Emeritus at the   University of Texas . Folk's sandstone (clastic) classification Edit Folk's philosophy is that the name of a rock must convey as much information as possible without being a complete description. For this, he proposed five important properties of sandstones to use as defining characteristics. These five properties are: grain size, chemically precipitated cements, textural maturity, miscellaneous transported constituents, and clan designation. Folk's fivefold name must be in the following format: (Grain size): (chemically precipitated cements) (textural maturity) (miscellaneous transported constituents) (clan designation) However, Folk stated that cements and miscellaneous transported constituents are optional categories as they are not always o...
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