sedimentary

Agate

Silicon dioxide, SiO2

Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, microcrystalline quartz structure with conchoidal fracture.

Identified November 13, 2026More sedimentary →

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Physical properties

Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, microcrystalline quartz structure with conchoidal fracture.

Formed by the deposition of silica from groundwater in the cavities of igneous and sedimentary rocks over millions of years.

Commonly used in ornamental jewelry, carved items, tumbling, and precision instruments like mortars and pestles.

Agate bands represent successive layers of fluid solutions entering a cavity, creating distinct colored patterns.

Identify by its waxy luster, microcrystalline banding, and resistance to steel. Found worldwide, especially in volcanic rock cavities.

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

Sandstone or Siltstone

Arenite (if sandstone)

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Shale

Fissile Sedimentary Rock

Sandstone

Arenite

Shale

Clastic sedimentary rock