sedimentary

Quartz Geode

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, white to clear coloration, vitreous luster, and trigonal crystal structure with conchoidal fracture.

Identified November 14, 2026More sedimentary →

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Physical properties

Hardness of 7 on the Mohs scale, white to clear coloration, vitreous luster, and trigonal crystal structure with conchoidal fracture.

Formed when mineral-rich groundwater deposits silica inside hollow cavities of sedimentary or volcanic rocks over millions of years.

Used in decorative displays, crystal healing, lapidary arts, and as a popular specimen for mineral collectors.

Geodes start as hollow nodules where microcrystalline silica lines the cavity walls before growing larger quartz crystals inward.

Identified by its outer weathered rind and sparkling interior crystal cavity; commonly found in limestone formations 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

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