chert

American  

[churt] / tʃɜrt /

noun

1. a compact rock consisting essentially of microcrystalline quartz.

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chert British  

/ tʃɜːt /

noun

1. Also called: hornstone.  a microcrystalline form of silica usually occurring as bands or layers of pebbles in sedimentary rock. Formula: SiO 2 . Varieties include flint, lyddite (Lydian stone)

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chert Scientific  

/ chûrt /

1. A hard, brittle sedimentary rock consisting of microcrystalline quartz. It is often reddish-brown to green but can also occur in a variety of other colors, especially white, pink, brown, or black. Chert often contains impurities such as calcium, iron-oxide, or the remains of silica-rich organisms. It usually occurs as nodules in limestone and dolomite and has curved fractures.

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Other Word Forms

• cherty adjective

Etymology

Origin of chert

First recorded in 1670–80; origin uncertain

Example Sentences

Early in the 1970s, a paleontologist working on the outskirts of an Indian village found small, bead-like fossils embedded in the gray chert dotting the surrounding fields.

From Science Daily • Dec. 19, 2023

Scientists have been debating whether this 3.5 billion-year-old black chert, which looks almost like a slab of marble, contains microbes of early life or just molecules leftover from non-biological processes.

From Salon • Sep. 26, 2023

Anyone found hitting the pale, more recently formed chert stone is strongly discouraged because it splinters, making it hazardous and impossible to split successfully.

From BBC • Sep. 9, 2023

They analyzed the projectile point and found it was made of Hozomeen chert, a sedimentary rock specific to the North Cascades.

From Seattle Times • Mar. 22, 2022

An eruption of Mount Elgon about seven million years ago had buried the rain forest in ash, and the logs had been transformed into opal and chert.

From "The Hot Zone" by Richard Preston