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Chert nodule within soft limestone at Akçakoca, Turkey. Nodular chert is most common in limestone but may also be found in shales [38] and sandstones. [25] It is less common in dolomite. [1] Nodular chert in carbonate rocks is found as oval to irregular nodules. These vary in size from powdery quartz particles to nodules several meters in size.
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. Examples include pyrite nodules in coal, a chert nodule in limestone, or a phosphorite nodule in marine shale.
For stone tools and flintlock strikers, chert is worked using a fabricator such as a hammerstone to remove lithic flakes from a nucleus or core of tool stone. Stone tools can then be further refined using wood, bone, and antler tools to perform pressure flaking. For building work a hammer or pick is used to split chert nodules supported on the lap.
A recent article by Lycett and Eren (2013) statistically shows the efficiency of the Levallois technique which at times has been called into question. Lycett and Eren created 75 Levallois flakes from 25 Texas Chert nodules.
The Corriganville Limestone was first described by J. W. Head in 1972 as part of the Helderberg Group in Allegany County, Maryland, as a gray limestone with chert. [11] C. R. Wood first mapped it as part of the Old Port Formation in Pennsylvania. [12] The type locality is a railroad cut 0.3 mi southeast of Corriganville, Alleghany County ...
Chert is a siliceous (silica) stone, a variety of quartz similar to flint but more brittle. It naturally occurs as large, flat, elliptically shaped nodules in creek beds, and sometimes as hill-top residuum. The nodules were formed as part of the Ullin limestone formation during the Mississippian geologic period (roughly 359 to 318 million years ...
[34] [35] Septarian nodules are characteristically found in carbonate-rich mudrock. They typically show an internal structure of polyhedral blocks (the matrix) separated by mineral-filled radiating cracks (the septaria) which taper towards the rim of the concretion. The radiating cracks sometimes intersect a second set of concentric cracks.
Limestone, Chert: Location; Region ... as well as occasional chert nodules. [2] Stratigraphy. This section includes a list of general references, ...