Where is Chert with Quartz Geode found?
Chert (cryptocrystalline quartz) with macrocrystalline quartz
Got a photo? Identify rocks instantly with the Rockby app
Open the appChert with Quartz Geode 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 with Quartz Geode
Keokuk Geodes, Iowa, USA
Famous for geodes found in Mississippian-age limestones, often with chert exteriors and interiors lined with quartz, calcite, or other minerals.
Indiana, USA
Similar to Keokuk geodes, found in Mississippian carbonate rocks.
Brazil
Known for large amethyst and quartz geodes, though often found in volcanic rocks, some sedimentary occurrences with chert are also present.
Mexico
Various localities produce geodes, including some with chert exteriors.
Collecting tips
- Look for Nodule Shapes. Chert geodes often appear as rounded to irregular nodules or concretions within sedimentary host rocks, particularly in weathered outcrops or stream beds where they have eroded out.
- Check for Weight and Sound. Geodes are often lighter than solid rock of the same size due to their hollow interior. Tapping them gently can sometimes produce a hollow sound, indicating a cavity.
- Examine Broken Surfaces. Look for naturally broken geodes or fragments that reveal the crystalline interior. The contrast between the dull chert and sparkling quartz is a key indicator.
- Associated Geology. Search in areas known for chert-bearing limestones, dolomites, or shales. Riverbeds and eroded hillsides are good places to find weathered-out specimens.
Quick Check
- Color:
- Variable chert exterior (white, gray, brown, black, red); colorless to white (or tinted) quartz interior.
- Luster:
- Dull to waxy exterior; vitreous interior.
- Streak:
- White (for both chert and quartz).
Explore Chert with Quartz Geode
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.