sedimentary

Agate

Silicon dioxide (SiO2)

Mohs hardness of 6.5-7, waxy luster, microcrystalline quartz structure, conchoidal fracture, and distinct multicolored banding.

Identified October 31, 2026More sedimentary →

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Physical properties

Mohs hardness of 6.5-7, waxy luster, microcrystalline quartz structure, conchoidal fracture, and distinct multicolored banding.

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

Used extensively in jewelry, ornamental carvings, decorative items, and precision laboratory instruments.

Agate is a variety of chalcedony and was highly valued in antiquity for signet rings and talismans.

Identified easily by its translucent appearance and concentric color bands; found worldwide, particularly 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

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)