sedimentary

Quartz Geode

Silicon Dioxide (SiO2) in sedimentary host rock

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale) for crystals; Color: Clear to white crystalline interior, tan/brown exterior rind; Luster: Vitreous (glassy) crystals to earthy exterior; Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture.

Hardness: 7 (Mohs scale) for crystals
Color: Clear to white crystalline interior, tan/brown exterior rind
Luster: Vitreous (glassy) crystals to earthy exterior

Identified July 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as secondary structures within sedimentary or volcanic rocks. They begin as hollow cavities in the rock (bubbles or rotted organic matter) which are filled over millions of years by mineral-rich water precipitating crystals inward.

Uses & applications

Primarily used for geological education, home decor, metaphysical collection, and lapidary art including bookends and jewelry slices.

Geological facts

Geodes are unique because they are hollow, though some, like this one, can be nearly solid (often called 'nodules' or 'solid geodes' when entirely filled). The word 'geode' comes from the Greek word 'Geoides' meaning 'earth-like'.

Field identification & locations

Identify by the rough, cauliflower-like exterior and hollow or crystalline core. Commonly found in limestone deserts or volcanic ash beds. Collectors look for pieces that feel lighter than they look (indicating a hollow center).