sedimentary

Agate

Silicon dioxide (Chalcedony), SiO2

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

Identified October 23, 2026More sedimentary →

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Physical properties

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

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

Widely used for ornamental objects, jewelry, decorative carvings, and laboratory mortars due to its durability.

Agate is a variety of chalcedony that typically forms in concentric bands, creating unique natural patterns.

Identify by its waxy luster, hardness, and banded or translucent appearance. Commonly found worldwide 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)