sedimentary
Geode
Silicon dioxide (Quartz/Chalcedony) concretion
Hardness of 7 on the Mohs scale, brownish or weathered exterior with a rough, bumpy texture, often hollow or mineral-filled inside, vitreous to dull luster.
Identified More sedimentary →
Explore Geode in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 7 on the Mohs scale, brownish or weathered exterior with a rough, bumpy texture, often hollow or mineral-filled inside, vitreous to dull luster.
Formation & geological history
Formed in cavities in sedimentary and volcanic rocks through the groundwater deposition of silica or carbonate minerals over millions of years.
Uses & applications
Popular among rockhounds and mineral collectors, often cut and polished to display internal crystal structures, used in ornamental items and jewelry.
Geological facts
Geodes start as hollow bubbles in rock, such as animal burrows, tree roots, or gas pockets in lava, which slowly line up with mineral crystals over geologic time.
Field identification & locations
Found worldwide in limestone formations, volcanic ash beds, and deserts; often identified by their rounded, potato-like shape and unusually light weight for their size.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary