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Mozarkite is a form of chert . It is the state rock of Missouri. The name is a portmanteau, formed from Mo (Missouri), zark , and ite (meaning rock). [1] Mozarkite consists essentially of silica (quartz - SiO 2) with varying amounts of chalcedony. It has won distinction as a particular form or variety of chert because of its unique variation of ...
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]
Narbona Pass Chert is finely textured and has regular breakage patterns that make it an excellent material for making stone tools and weapon heads by flintknapping. The chert has a variety of colors including white, pale blue, dark gray and pink. [10]
The Grassy Knob Chert upper sections are yellowish grey to light olive grey limestone, interbedded with cherty inclusions. Moving lower the amount of chert increases and the color changed to light grey with some olive grey mottling. This formation is generally the same age as the Oriskany Formation of the Appalachian Basin. [2]
It is often an impure variety of chert containing clay and calcareous matter. [1] Porcellanite has been found, for example, in Northern Ireland, Poland and the Czech Republic. Porcellanite is also commonly found in the Northern Territory of Australia. There, it comes in a variety of colours, primarily white, yellow, red and purple.
Mill Creek Chert is a tough, coarse-grained chert, usually brown or gray in color, and occurs as large tabular shaped nodules. [3] The best archaeological evidence states that maize (corn) first entered the United States from Mexico around 800 CE.
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Radiolarites are very brittle rocks and hard to split. They break conchoidally with sharp edges. During weathering they decompose into small, rectangular pieces. The colors range from light (whitish) to dark (black) via red, green and brown hues. Radiolarites are composed mainly of radiolarian tests and their fragments.