sedimentary
Agate
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline quartz structure, conchoidal fracture, and specific gravity around 2.6.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline quartz structure, conchoidal fracture, and specific gravity around 2.6.
Formation & geological history
Formed by the deposition of silica from groundwater in cavities of igneous or sedimentary rocks, typically over millions of years.
Uses & applications
Used primarily in lapidary arts, ornamental carvings, jewelry, and for precision instruments like mortar and pestles.
Geological facts
Agate bands represent successive layers of silica deposition, often reflecting changes in water chemistry or temperature during formation.
Field identification & locations
Identify by its distinctive concentric banding and waxy luster. Found worldwide in volcanic rock cavities and river gravels.
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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
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary