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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.
This band was composed of Charly (real name Calogero Maurici), his brother Jacky (Gioacchino Maurici) and their childhood friends Francis (Francis Maggiulli) and Fred Mattia who left the group six months after its foundation.
Fossil Inzeria intia stromatolites from the Bitter Springs Group. The Bitter Springs Group, also known as the Bitter Springs Formation is a Precambrian fossil locality in Australia, which preserves stromatolites and microorganisms in silica. [3]
At the Silurian/Devonian boundary black cherts (locally called lydites or flinty slates) developed from radiolarians mainly in the Franconian Forest region and in the Vogtland in Germany. Of great importance are the novaculites from Arkansas , Oklahoma and Texas which were deposited at the close of the Devonian.
The chert was discovered by William Mackie while mapping the western margin of the Rhynie basin in 1910–1913. [6] Trenches were cut into the chert at the end of this period, and Robert Kidston and William Henry Lang worked furiously to describe the plant fossils between 1917 and 1921. [6]
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.
Flintknapping a stone tool. Knapping is the shaping of flint, chert, obsidian, or other conchoidal fracturing stone through the process of lithic reduction to manufacture stone tools, strikers for flintlock firearms, or to produce flat-faced stones for building or facing walls, and flushwork decoration.
Sediments are usually contiguous with VMS deposits in some form or another and typically are present as (manganiferous) cherts and chemical sediments deposited within a submarine environment. The hanging wall to the deposit can be volcanic units essentially contiguous and coeval with the footwall rocks, indicating mineralisation was developed ...