sedimentary
Geode (Unopened)
Chalcedony/Quartz Geode (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs), Color: Tan to grey exterior (vuggy/bumpy texture), Luster: Dull/Earthy exterior, Crystal Structure: Hexagonal (inside), Specific Gravity: ~2.65
Identified More sedimentary →
Explore Geode (Unopened) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs), Color: Tan to grey exterior (vuggy/bumpy texture), Luster: Dull/Earthy exterior, Crystal Structure: Hexagonal (inside), Specific Gravity: ~2.65
Formation & geological history
Formed in sedimentary rock cavities (typically limestone) via groundwater precipitation of minerals over millions of years, often in the Mississippian or Cenozoic periods.
Uses & applications
Collector specimens, decorative displays, lapidary use, and educational tools.
Geological facts
Geodes are often hollow, containing a 'rattle' sound if crystals have broken loose inside. The term 'geode' comes from the Greek word 'Geoides' meaning 'earth-like'.
Field identification & locations
Identified by their round or egg-like shape and cauliflower-like exterior texture. Commonly found in stream beds or limestone deposits in states like Iowa, Indiana, or Illinois in the US.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary