Chert
This content was prepared by Sarah Bingham, Rowan University Class of 2021
Chert is also an umbrella term
Chert is often used as an umbrella term for all microcrystalline quartz rocks
Flint and chert are sometimes considered interchangeable types
Flint occurs in chalk and is darker in color
Grey chert is lighter in color and occurs in limestone
Chert is considered lesser in quality
These impurities in the chert create the gray color
Why was it used for tools?
Chert is very hard
It fractures very cleanly
Breaks down a plane to create clean flakes
These flakes have very sharp edges
Also creates sparks when struck against iron
Chert could be used to start fires
What is Gray Chert?
A sedimentary rock that is a form of silicon dioxide (SiO₂) also known as quartz
Commonly found in carbonate rocks
Created as nodules of crystals congregate with water flow
Found in areas that used to be deep ocean beds
Can also be created from silicon skeletons of oceanic fossils
Where is it found in NJ?
Gray Chert is found in New Jersey's limestone deposits
The U.S. Geological Survey contains a full list of places where it has been documented including:
Allentown Dolomite
Buttermilk Falls Limestone
Want to Learn More?
Geology.com
U.S. Geological Survey
Luedtke, Barbara E. (1992). An archaeologist's guide to chert and flint. Los Angeles: Institute of Archaeology, University of California. ISBN 0-917956-75-3.