sedimentary

Geode (Unopened)

SiO2 (Quartz-filled Sedimentary Nodule)

AI-generated identification · may be incorrect

Hardness: 7 (inner quartz), Color: Ocher, brownish-grey exterior, Luster: Dull/earthy exterior, Crystal structure: Trigonal (internal), SG: 2.6-2.7. It has a rough, pitted cauliflower-like texture.

Identified June 14, 2026More sedimentary →

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Physical properties

Hardness: 7 (inner quartz), Color: Ocher, brownish-grey exterior, Luster: Dull/earthy exterior, Crystal structure: Trigonal (internal), SG: 2.6-2.7. It has a rough, pitted cauliflower-like texture.

Formation & geological history

Formed via the precipitation of minerals into internal cavities of sedimentary rocks (like limestone) or volcanic ash. These cavities are often created by gas bubbles or decaying organic matter over millions of years.

Uses & applications

Primarily for mineral collecting, education, and as decorative lapidary items once cut and polished to reveal the crystal interior.

Geological facts

The word 'Geode' comes from the Greek word 'Geoides' meaning earth-like. Some geodes are 'thunder eggs' which are solid, while true geodes must have a hollow interior.

Field identification & locations

Identify in the field by their rounded, bumpy 'cauliflower' exterior and they often feel lighter than a solid rock of the same size. Commonly found in desert regions or limestone beds.