Science

What is a chert nodule?

By: Carlos BarceloUpdated: February 20, 2021

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Chert is a sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). It occurs as nodules, concretionary masses, and as layered deposits. Chert breaks with a conchoidal fracture, often producing very sharp edges.

Herein, how do chert nodules form?

Chert and flint nodules are often found in beds of limestone and chalk. They form from the redeposition of amorphous silica arising from the dissolution of siliceous spicules of sponges, or debris from radiolaria and the postdepositional replacement of either the enclosing limestone or chalk by this silica.

Also, how do you identify chert?

Chert has four diagnostic features: the waxy luster, a conchoidal (shell-shaped) fracture of the silica mineral chalcedony that composes it, a hardness of seven on the Mohs scale, and a smooth (non-clastic) sedimentary texture.

What is chert used for today?

In today's world, chert has very few uses, but many ancient cultures used it to make tools for cutting and scraping and also used it to make weapons like arrowheads and ax heads. It is very hard and durable and the edges of chert are very sharp. The most abundantly found variety of chert is “common chert”.

Where is chert commonly found?

Thick beds of chert occur in deep marine deposits. These thickly bedded cherts include the novaculite of the Ouachita Mountains of Arkansas, Oklahoma, and similar occurrences in Texas and South Carolina in the United States.

Related

Is flint and chert the same thing?

Flint Is A Variety of Chert
Although there is a lot of confusion on this, chert refers to cryptocrystalline or polycrystalline quartz that usually forms as nodules in limestone. Flint is reserved for such material that forms in chalk or marl. Flint is simply a type of chert.

What does chert consist of?

Chert is a sedimentary rock consisting almost entirely of silica (SiO 2), and can form in a variety of ways. Biochemical chert is formed when the siliceous skeletons of marine plankton are dissolved during diagenesis, with silica being precipitated from the resulting solution.

How much does chert cost?

Wikipedia says: "Hauled prices for chert of less than $10 - $15 per ton are not uncommon in many parts of the U.S.", so, unless you live close to one of the consuming industries and can keep transport costs low, it doesn't sound like a very profitable operation.

What color is chert?

Chert occurs in a wide variety of colors. Continuous color gradients exist between white and black or between cream and brown. Green, yellow, orange, and red cherts are also common. The darker colors often result from inclusions of mineral matter and organic matter.

How is chert created?

Chert can form when microcrystals of silicon dioxide grow within soft sediments that will become limestone or chalk. Chert formed in this manner is a chemical sedimentary rock. Diatoms are microscopic, single-celled algae that live in marine or fresh water. They produce hard parts made of silicon dioxide.

What is a flint nodule?

Flint nodule: Flint is a variety of microcrystalline or cryptocrystalline quartz. It occurs as nodules and concretionary masses, and less frequently as a layered deposit. It breaks consistently with a conchoidal fracture and was one of the first materials used to make tools by early people.

What is the grain size of chert?

Chert has the general physical properties of quartz. Texture - non-clastic. Grain size - cryptocrystalline, cannot be seen except under very high magnification.

What is the texture of chert?

Chert is a hard, dense sedimentary rock that is composed of microcrystalline, cryptocrystalline and microfibrous quartz (SiO2). It is characterized by a semivitreous to dull luster and characteristical splintery to conchoidal fracture. Chert occurs in three forms: Nodular. massive.

What minerals make up chert?

In petrology the term "chert" is used to refer generally to all rocks composed primarily of microcrystalline, cryptocrystalline and microfibrous quartz. The term does not include quartzite. Chalcedony is a microfibrous (microcrystalline with a fibrous structure) variety of quartz.

What is the difference between chert and jasper?

Chert is clearly a rock as it forms large /bedded deposits with variable mineralogy, though dominated by quartz, but under a thin section is is usually obviously a mixture. Flint is very similar but usually nodular, and Jasper is a vague lapidary term for various fine grained siliceous rocks.

How old is chert rock?

The Rhynie Cherts in Scotland contain remains of the oldest land ecosystem from nearly 400 million years ago early in the Devonian Period. And the Gunflint Chert, a unit of banded iron formation in western Ontario is famous for its fossil microbes, dating from the Early Proterozoic time some two billion years ago.

How is radiolarian chert formed?

When radiolaria die, their tiny skeletons fall to the ocean floor, forming an ooze. This ooze eventually hardens into rock. The chert forms horizontal layers about 5 –15 cm thick. It took about 1,000 years for a 1 mm thickness of chert to form!

What does dolostone look like?

It is thought to form by the postdepositional alteration of lime mud and limestone by magnesium-rich groundwater. Dolomite and limestone are very similar rocks. They share the same color ranges of white-to-gray and white-to-light brown (although other colors such as red, green, and black are possible).

What type of rock is Flint?

sedimentary rocks

What type of sedimentary rock is chert?

Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (SiO2). It occurs as nodules and concretionary masses, and less frequently as a layered deposit. It breaks with a conchoidal fracture, often producing very sharp edges.