Where is Fossiliferous Chert found?
Chert with fossil inclusions
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Open the appFossiliferous 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 Fossiliferous Chert
North America
Widely distributed across the United States (e.g., Burlington Chert in the Midwest, Fort Payne Chert in the Southeast, Franciscan Complex in California) and Canada, often associated with Paleozoic and Mesozoic marine sedimentary formations.
Europe
Common in various countries, including the UK (e.g., Carboniferous Limestone formations), France, Germany, and Russia, often in association with ancient marine platforms.
Asia
Found in numerous locations, particularly in regions with extensive marine sedimentary records, such as China, Japan, and parts of Southeast Asia.
Australia
Present in various sedimentary basins, often associated with ancient marine environments.
Collecting tips
- Look in Sedimentary Outcrops. Search for fossiliferous chert in areas with exposed sedimentary rock layers, particularly those containing limestone, shale, or ancient marine deposits. Road cuts, riverbeds, and quarries are good places to start.
- Identify Chert Characteristics. First, identify chert by its hardness (scratches glass), conchoidal fracture, and waxy to dull luster. Then, carefully examine the rock for visible fossil inclusions or outlines.
- Examine Weathered Surfaces. Weathering can sometimes highlight fossils, making them more visible on the surface of the chert due to differential erosion or color changes.
- Use a Hand Lens. A hand lens (10x magnification) is invaluable for spotting smaller fossils or fossil fragments that might not be obvious to the naked eye.
- Check for Silicified Fossils. In some cases, the fossils themselves may be silicified and stand out in relief or by color contrast from the surrounding chert matrix.
Quick Check
- Color:
- Variable (gray, black, brown, tan, white, red), often with visible fossil outlines or structures.
- Luster:
- Dull to waxy, vitreous on fresh breaks.
- Streak:
- White
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