Where is Oolitic Chert found?
Sedimentary rock, variety of chert with oolitic texture
Got a photo? Identify rocks instantly with the Rockby app
Open the appOolitic 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 Oolitic Chert
North America
Found in various states, including Indiana (Mississippian age Salem Limestone), Kentucky, Missouri, and parts of the Appalachian Basin, where oolitic limestones have been silicified.
Europe
Occurs in regions with extensive carbonate platforms, such as parts of the UK (e.g., Jurassic oolitic limestones), France, and Germany, where chertification has taken place.
Middle East
Present in some carbonate sequences, particularly in areas with a history of shallow marine deposition and subsequent diagenesis.
Collecting tips
- Look for Oolitic Limestone Outcrops. Oolitic chert is a silicified version of oolitic limestone. Therefore, areas known for oolitic limestone formations are good places to search for oolitic chert, especially where diagenetic processes have been active.
- Examine Weathered Surfaces. On weathered surfaces, the oolitic texture may be more pronounced as the chert matrix might erode slightly differently than the ooids, or vice-versa. The hardness of chert also makes it resistant to weathering, so it may stand out in outcrops.
- Check Stream Beds and Gravel Pits. Resistant chert nodules and fragments, including oolitic chert, can be transported and concentrated in stream beds, river gravels, and glacial till deposits.
- Perform a Hardness Test. Chert is hard (Mohs 6.5-7). If you suspect a rock is oolitic chert, try to scratch glass with it. If it scratches glass and exhibits an oolitic texture, it's likely oolitic chert. This distinguishes it from softer oolitic limestones.
Quick Check
- Color:
- Variable (gray, white, tan, brown, black)
- Luster:
- Dull to waxy, vitreous on fresh fracture
- Streak:
- White
Explore Oolitic Chert
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.