sedimentary

Agate

Silicon dioxide (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, waxy luster, conchoidal fracture, and microscopic fibrous quartz structure showing distinct color banding.

Identified October 18, 2026More sedimentary →

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Physical properties

Hardness of 6.5 to 7 on the Mohs scale, waxy luster, conchoidal fracture, and microscopic fibrous quartz structure showing distinct color banding.

Formed by the deposition of silica from groundwater in cavities of ancient volcanic or sedimentary rocks, often over millions of years.

Widely used in ornamental carvings, jewelry, decorative items, and precision instruments like mortars and pestles.

Agate is one of the oldest known talismanic stones, historically used by ancient civilizations for amulets and seals.

Identified by its distinctive concentric color bands and waxy sheen; commonly found in volcanic regions 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)