Chert

Classification：Sedimentary Rock

A hard and dense sedimentary rock, mainly composed of cryptate quartz. They are mainly distributed in carbonate rocks. The flint is a dark colored flint.

Chert, commonly known as "flint stone", is composed of cryptic quartz, which is a relatively common siliceous rock. It is dense and hard. It is mostly gray and black. After it is broken, it has shell shaped fracture. According to its state of existence, it is divided into two types: layered Chert: most of them are symbiotic with phosphorous and manganese bearing clay layers, stratified existence, one layer thickness is not too thick. But the total thickness can reach hundreds of meters, with the difference between massive and oolitic. Tuberculate Chert: more prolific in limestone, there are nodular, oval, rod, disc, gourd like, irregular shape and other nodules, usually only 5-15 centimeters, large up to 1-2 meters. Because of its hard and broken fracture, Chert was the earliest primitive man of stone age, most of which were made by Chert.

Chert English name Quartz var. Chert, commonly known as flint, is a relatively common siliceous rock, dense and hard, mostly gray and black. It is a quartz and a very fine silicon oxygen mineral with trace impurities. Chert has a uniform and fine texture, it is hard and crisp, and the fracture is shellfish. These features are used by the ancients to produce the stone age of the tools of human use. Chert can be used to build roads and act as concrete aggregates, and people use Chert blocks as abrasives to grind other industrial raw materials, and the excellent Chert will also be treated as low gems. Chert and some variants, such as jade, chalcedony, agate, black Chert and novaculite. In some rocks, Chert is a form of tuberculosis. When the corrosion resistant rocks are weathered, the corrosion resistant Chert is exposed and concentrated together to form a rich area. The name of [1] is derived from the unknown meaning of German quarz.

Chemical composition:
SiO2 and Si46.7% contain different amounts of mechanical mixture of gaseous, liquid and solid substances.

Optical properties:
Uniaxial crystal (+), No=1.543-1.545, Ne=1.552-1.554, double reflectivity =0.0090..

Distribution:
All parts of the world are widely distributed.

Identification characteristics:
Alpha quartz is characterized by its crystal form, no cleavage, shell fracture and hardness. If it is transformed from beta quartz, it will maintain the illusion of six sides and two cones.

Cause of origin:
Alpha quartz is widely distributed in nature, and is the main rock forming mineral of many igneous rocks, sedimentary rocks and metamorphic rocks. Beta quartz occurs in acidic igneous rocks or shallow rocks, often with phenocrysts. It belongs to colloidal products of low-temperature hydrothermal fluids, mainly produced in pores of extrusive rocks.

Crystal morphology:
The three party cube surface crystals are usually developed into intact cylindrical crystals. The common form is: six square column m, rhombohedral R and Z, three party double cone s and three party square surface x, etc., the cylinder has cross striation.

Crystal structure:
Crystal system and space group: three square crystal system of alpha quartz, P312; beta quartz six square crystal system, P622; crystal cell parameters: alpha quartz: a0=4.91, c0=5.40; beta quartz: a0=5.01, c0=5.47; powder crystal data: 3.342 (1) 4.257 (0.22) 1.8179 (0.14))

Classification:
Chert (quartz variant) Quartz var. Chert
According to its state of existence, it is divided into two types:
Layered Chert: most of them are symbiotic with phosphorous and manganese bearing clay layers. They are stratified, and the thickness of the monolayer is small, but the total thickness can be up to hundreds of meters, with the difference of lump and oolitic.
Tuberculate Chert: more prolific in limestone, there are nodular, oval, rod, disc, gourd like, irregular shape and other nodules, usually only 5-15 centimeters, large up to 1-2 meters. [2]

Main uses:
As a result of the hard and broken fracture, Chert is the earliest primitive man of stone age, most of which are made by Chert, and Chert and iron strike will produce sparks, so it is also used as a fire tool for ancient people. In ancient China, a small piece of Chert and a steel "sickle" were used. Chert is also called flint. Chert gun also uses trigger to strike flint and cause gunpowder. In modern times, the hard property of Chert is used to make Chert as the raw material of grinding.