sedimentary

Geode (Unopened)

Silicon Dioxide (SiO2) in sedimentary vugs

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Dirty white/brown exterior with possible quartz inside, Luster: Dull/earthy exterior, Crystal structure: Amorphous/microcrystalline exterior, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Identified February 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by precipitation of minerals from hydrothermal fluids or groundwater into hollow cavities within sedimentary or volcanic rock. Often found in limestone or shale beds.

Uses & applications

Primarily used as decorative display pieces, for geological education, and by mineral collectors. When cracked open, the inside crystals may be used in jewelry.

Geological facts

Geodes are known as 'treasure chests' of the earth. Until they are broken open, it is impossible to know if they contain clear quartz, purple amethyst, or are hollow/solid clusters of minerals.

Field identification & locations

Identify in the field by their rounded, nodular shape which differs from the surrounding bedrock; they often feel lighter than they look if they are hollow. Common in desert environments or limestone quarries.