sedimentary

Agate

Silicon Dioxide (SiO2)

Mohs hardness of 6.5 to 7, exhibits various colors like brown, grey, and amber with a waxy to vitreous luster and microcrystalline crystal structure.

Identified October 23, 2026More sedimentary →

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Physical properties

Mohs hardness of 6.5 to 7, exhibits various colors like brown, grey, and amber with a waxy to vitreous luster and microcrystalline crystal structure.

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

Used primarily in jewelry, ornamental carvings, and lapidary art.

Agate is a variety of chalcedony and often displays distinct concentric banding patterns.

Identified by its conchoidal fracture and waxy luster, commonly found in volcanic rock cavities worldwide.

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

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)