sedimentary
Agate
Silicon dioxide (chalcedony, SiO2)
AI-generated identification · may be incorrectMohs hardness of 6.5 to 7; typically multicolored or banded; waxy to vitreous luster; cryptocrystalline structure with conchoidal fracture.
Identified More sedimentary →
Explore Agate in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness of 6.5 to 7; typically multicolored or banded; waxy to vitreous luster; cryptocrystalline structure with conchoidal fracture.
Formation & geological history
Formed by the deposition of silica from groundwater in cavities of igneous and sedimentary rocks, often over millions of years.
Uses & applications
Widely used for ornamental objects, jewelry, polished specimens, and industrial knife-edge bearings.
Geological facts
Agate bands represent successive layers of deposition in cavity walls. Named after the Achates River in Sicily where it was found in antiquity.
Field identification & locations
Identified by waxy luster, conchoidal fracture, and distinct banding patterns; commonly found in riverbeds, volcanic regions, and gravel deposits worldwide.
More like this
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