chert


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Related to chert: Dolostone, micrite

chert:

see flintflint,
variety of quartz that commonly occurs in rounded nodules and whose crystal structure is not visible to the naked eye. Flint is dark gray, smoky brown, or black in color; pale gray flint is called chert.
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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Chert

 

a mineral formation consisting of crystalline and amorphous silica (opal, chalcedony, or quartz). Chert is widespread in nature in the form of concretions, nodules, and seams that either lie parallel with the enclosing limestone and chalk deposits or cut across bedding. It is formed either by diagenesis of deposits, by catagenesis of rocks, or by weathering. It has a hardness of 7 on the mineralogical scale and breaks with a conchoidal fracture. Because of its ability to form a sharp cutting edge when chipped, chert (flint) was used by man from the most ancient times to the Iron Age to make stone tools.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

chert

[chərt]
(petrology)
A hard, dense, sedimentary rock composed of fine-grained silica, characterized by a semivitreous to dull luster and a splintery to conchoidal fracture; commonly gray, black, reddish brown, or green. Also known as hornstone; phthanite.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

chert

A very fine-grained dense rock consisting of chalcedony or opal, often with some quartz, and sometimes with calcite, iron oxide, organic matter, or other impurities; has a homogeneous texture and white, gray, or black color; some of its constituents may react with cement alkalies and therefore may be undesirable as concrete aggregate for exposed concrete in northern climates.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Many tools are fabricated in a green radiolarian chert or in Ramah quartzite.
Indeed, the concretions display exceptionally low contents of [SIGMA]REE, slight LREE enrichment, and occasional positive Eu anomalies, quite different from the patterns observed in the sedimentary chert (Figure 4).
The chemical and mineralogical compositions of chert samples were obtained by means of X-ray fluorescence (XRF) and X-ray powder diffraction (XRPD), respectively.
It was only much later, during the course of fieldwork focusing on stone vocabulary, that I ascertained that its meaning was in fact a raw material type meaning 'chert', and that it could be used of chert in its raw state or of any object manufactured of chert.
There is a heavy emphasis on the use of quartz and rhyolite in the debitage, compared to an emphasis on chert and rhyolite for formal tools (Table 6).
Period Group Formation Lithology Aquifer potential Lower Balqa Umm Rijam Chert, Semi aquifer Tertiary (B4) limestone Muwaqqar Chalk, Aquitard (B3) Marl Al Hasa Phosphate Good (B2a) aquifer Amman Silicified Aquifer (B2b) Limestone interrupted Wadi Ghudran Chalk, aquiclude (Bl) Chalky marl Cretaceous Ajlun Wadi As Sir Limestone good aquifer (A7) Shueib Marly Aquitard to badly (A5-6) Limestone developed aquifer Hummar Dolomitic Semi aquifer (A4) Limestone Fuhais Marl Aquitard, partly (A3) semi aquifer Na'ur Marly Semi aquifer (Al-2) Limestone Period Group Thickness (meter) Lower Balqa 70 m Tertiary 60-70 m 60 m 50 m 20 m Cretaceous Ajlun 20 m No outcrop No outcrop No outcrop No outcrop Table 2.
The two ball chert zones in the middle Fredonia occur in a lithographic to finely crystalline limestone interval; white to gray color and includes spirifer brachiopods, horn corals, and the rugose coral (Lithostrotion harmodites).
Keywords: obsidian, New Britain, chert, stemmed tools, mid-Holocene, sources
Also, in some places around Alston, the Scar Limestone is rich in nodules of chert - essentially the same hard material as flint.
However, a new study has claimed that the Apex Chert formation found in Western Australia's Pilbara region is not biological material at all.
9:45 CHERT HUNTING: MODELING PREHISTORIC LITHIC RESOURCE RANGES IN