mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: White to colorless crystals; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: White to colorless crystals
Luster: Vitreous (glassy)

Identified June 17, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: White to colorless crystals; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed as secondary mineral growth within hollow cavities (vesicles) in volcanic rock or sedimentary nodules. Mineral-rich groundwater seeps into these cavities, precipitating crystals over thousands of years.

Uses & applications

Primarily used as decorative specimens, for educational purposes, in rock collections, and occasionally in the metaphysical industry or minor jewelry elements.

Geological facts

Geodes are often referred to as 'thunder eggs' when they are filled solid. The name 'geode' comes from the Greek word 'geoides' which means 'earth-like'.

Field identification & locations

Identify by a rounded, cauliflower-like exterior and a hollow center lined with crystals. Common in volcanic ash beds or limestone deposits in regions like the American Midwest, Brazil, and Mexico.