sedimentary

Agate

Silicon dioxide (chalcedony, SiO2)

Hardness 6.5-7 on the Mohs scale, waxy luster, microcrystalline crystal structure, conchoidal fracture, and distinct banded patterns.

Identified November 14, 2026More sedimentary →

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Physical properties

Hardness 6.5-7 on the Mohs scale, waxy luster, microcrystalline crystal structure, conchoidal fracture, and distinct banded patterns.

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

Widely used in ornamental jewelry, decorative objects, precision instruments, and mortar pestles due to its durability.

Agate bands record changing environmental conditions during their slow formation inside volcanic gas vesicles.

Identified by its waxy luster, hardness, and colorful concentric banding; commonly found globally 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