sedimentary

Quartz Geode

Silicon dioxide (SiO2)

Hardness of 7 on the Mohs scale, transparent to white color, vitreous luster, and hexagonal crystal system.

Identified November 14, 2026More sedimentary →

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Physical properties

Hardness of 7 on the Mohs scale, transparent to white color, vitreous luster, and hexagonal crystal system.

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

Used in specimen collecting, decorative items, and jewelry-making.

Geodes start as hollow bubbles in rock, often formed from animal burrows, tree roots, or gas pockets in lava.

Easily identified by a rough, bumpy outer rock shell that reveals sparkling crystal points when cracked open.

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