sedimentary
Agate
Silicon dioxide (chalcedony, SiO2)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, and exhibits banded or translucent color patterns.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, and exhibits banded or translucent color patterns.
Formation & geological history
Formed by the deposition of silica from groundwater in the cavities of igneous and sedimentary rocks over millions of years.
Uses & applications
Widely used for ornamental objects, jewelry, decorative carvings, and in industrial bearings.
Geological facts
Agate is one of the most popular stones used in lapidary arts and was named by the Greek philosopher Theophrastus after the Achates River in Sicily.
Field identification & locations
Easily identified by its distinct concentric banding and conchoidal fracture; commonly found in volcanic rock cavities worldwide.
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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