mineral

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Hardness: 7 (Mohs scale); Color: Clear to white crystals; Luster: Vitreous/glassy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Clear to white crystals
Luster: Vitreous/glassy

Identified June 9, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Clear to white crystals; Luster: Vitreous/glassy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in voids created by gas bubbles in volcanic rock or cavities in sedimentary rock. Mineral-rich groundwater precipitates crystals over thousands to millions of years. This specimen appears to have a rhyolitic or sedimentary matrix base.

Uses & applications

Primarily used for geological education, home décor, collector specimens, and occasionally as a source for industrial silicon or glass-making if found in massive quantities.

Geological facts

Geodes are hollow, sub-spherical rocks containing inward-growing crystals. The word geode comes from the Greek word 'Geoides' meaning 'earth-like'. They can range from the size of a pea to several meters long.

Field identification & locations

Identify in the field by their rounded, bumpy exterior that sounds hollow when tapped. Common in desert environments like Utah, Mexico, and Brazil. Collectors should look for unusually light stones for their size.