mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: typically white, clear, or cloudy internally with a tan or gray outer rind; Luster: vitreous (glassy) inside, dull outside; Crystal structure: Trigonal/Hexagonal; Cleavage: none.

Hardness: 7 on Mohs scale
Luster: vitreous (glassy) inside, dull outside

Identified May 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed when mineral-rich groundwater seeps into hollow cavities in volcanic or sedimentary rocks. Over thousands to millions of years, silica precipitates out of the water to form crystals pointing inward.

Uses & applications

Highly popular for mineral collecting, education, decorative displays, jewelry, and as 'metaphysical' stones. Crushed quartz is used in commercial glassmaking and electronics.

Geological facts

The word 'geode' comes from the Greek word 'Geoides' meaning 'earth-like.' While they look like ordinary rocks on the exterior, they contain hidden crystal cathedrals inside.

Field identification & locations

Identify by looking for round or egg-shaped nodules that feel significantly lighter than solid rocks of the same size. Commonly found in desert regions of the US (Utah, Arizona), Mexico, and Brazil.