sedimentary

Quartz Geode

Silicon Dioxide (SiO2)

Hardness of 7 on Mohs scale, grayish-white exterior with transparent inner quartz crystals, vitreous luster, trigonal crystal system.

Identified November 4, 2026More sedimentary →

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Physical properties

Hardness of 7 on Mohs scale, grayish-white exterior with transparent inner quartz crystals, vitreous luster, trigonal crystal system.

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

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

Geodes start as hollow nodules or bubbles in rock where dissolved silica gradually crystallizes inward from the outer wall.

Identified by its rough, knobby exterior and hollow center lined with sparkling crystals; found globally in limestone and volcanic deposits.

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)