sedimentary
Agate
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectMohs hardness 6.5-7, waxy to vitreous luster, displays concentric color bands, cryptocrystalline crystal structure, specific gravity 2.6-2.7.
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Physical properties
Mohs hardness 6.5-7, waxy to vitreous luster, displays concentric color bands, cryptocrystalline crystal structure, specific gravity 2.6-2.7.
Formation & geological history
Forms by the deposition of silica from groundwater in cavities of igneous and sedimentary rocks over millions of years.
Uses & applications
Used primarily in ornamental jewelry, decorative carvings, and precision laboratory instruments.
Geological facts
Ancient civilizations used agate for intaglio seals and talismans, believing it warded off thirst and fever.
Field identification & locations
Identified by its distinct concentric banding and waxy luster; commonly found worldwide in volcanic rock cavities.
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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