Where is Chert found?

Chert occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.

Where to find Chert

Collecting tips

1. Look in Carbonate Rocks. Chert nodules are frequently found embedded within limestone and dolomite formations. Look for rounded or irregular masses that are harder and often darker than the surrounding rock.
2. Examine Stream Beds and Gravel Pits. Due to its hardness and resistance to weathering, chert often survives transport and can be found as pebbles and cobbles in river gravels and glacial till.
3. Check for Conchoidal Fracture. A key identifying feature is its characteristic conchoidal (shell-like) fracture, which produces sharp, curved edges. This can be observed on broken surfaces.
4. Test Hardness. Chert is harder than steel (Mohs hardness 7), so it will scratch glass and cannot be scratched by a steel knife.
5. Observe Luster. While variable, chert often has a waxy or dull luster, distinguishing it from the more vitreous luster of pure quartz crystals.

Quick Check

Color:

Variable (white, gray, black, brown, red, green)

Luster:

Waxy to dull, sometimes vitreous

Streak:

White

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