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Chert (/ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline 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]
The compaction of radiolarites is dependent on their chemical composition and correlates positively with the original SiO 2-content. The compaction factor varies generally between 3.2 and 5, which means that 1 meter of consolidated sediment is equivalent to 3.2 to 5 meters of ooze.
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1] [2] categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires. Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.
When opal silica accumulates faster than it dissolves, it is buried and can provide a diagenetic environment for marine chert formation. [8] The processes leading to chert formation have been observed in the Southern Ocean, where siliceous ooze accumulation is the fastest. [8] Chert formation however can take tens of millions of years. [7]
Jasper is the main component in the silica-rich parts of banded iron formations (BIFs) which indicate low, but present, amounts of dissolved oxygen in the water such as during the Great Oxidation Event or snowball earths. [16] The red bands are microcrystalline red chert, also called jasper.
Composition of gravel-size clasts they contain; Size range of gravel-size clasts present; The classification method depends on the type and detail of research being conducted. [1] [2] [5] A sedimentary rock composed largely of gravel is first named according to the roundness of the gravel.
Body composition is a breakdown of these three elements. Body composition refers to the percentages body fat, bone, and lean tissue mass (basically, the muscle, organs, water, and other types of ...
Banded iron formation from the Barberton Greenstone Belt, South Africa. A typical banded iron formation consists of repeated, thin layers (a few millimeters to a few centimeters in thickness) of silver to black iron oxides, either magnetite (Fe 3 O 4) or hematite (Fe 2 O 3), alternating with bands of iron-poor chert, often red in color, of similar thickness.