Chert Facts

Chert Facts
Chert is a microcrystalline sedimentary rock consisting mostly of silicon dioxide (SiO2) and can form in many different ways. It can form when microcrystals of silicon dioxide grow within soft sediments that will later become chalk or limestone. Chert is smooth to touch and usually glassy. It is a very hard rock and breaks with a conchoidal fracture and often produces very sharp edges.
Interesting Chert Facts:
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.
Chert is found in many colors. Most common colors are blue, green, red and yellow. White coloration usually indicates it contains carbonate impurities, while black indicates organic matter.
Darker color chert is often referred to as flint. It can be found in chalk or marly limestone formations and formed by a replacement of calcium carbonate with silica. It's commonly found as nodules.
Red to brown chert receive their color when it contains iron oxide and are then referred to as jasper. It is usually opaque to near opaque.
The most abundantly found variety of chert is "common chert". It is a variety of chert which forms in limestone formations by replacement of calcium carbonate with silica. It is considered to be less attractive for producing gem stones than flint.
When struck against steel, it produces a spark which results in heat. It makes an excellent tool for starting fires.
A primary historic use of chert and flint was to make a "flintlock gun". The firearm had a metal plate that produced a spark when struck with chert. It ignited a small reservoir containing black powder that discharged the firearm.
Chert was used in the late 1800's and early 1900's as grave markers or headstones.
Marble Bar Chert in Western Australia is considered one of the earliest and best preserved sedimentary successions on Earth.

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