sedimentary
Agate
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, and banded color patterns of translucent brown, white, and gray with cryptocrystalline structure.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, and banded color patterns of translucent brown, white, and gray with cryptocrystalline structure.
Formation & geological history
Formed by the deposition of silica from groundwater in cavities of igneous and sedimentary rocks over millions of years.
Uses & applications
Used primarily in jewelry, decorative carvings, and as a popular specimen for rock collectors.
Geological facts
Agates form in concentric layers inside ancient volcanic vesicles, preserving the chemical signature of ancient fluid flows.
Field identification & locations
Easily identified by distinct concentric bands and waxy luster; commonly found in riverbeds, glacial drift, and volcanic regions.
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Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary