mineral

Quartz Geode

Silicon Dioxide (SiO2) in Geodic habit

Hardness: 7 on Mohs scale. Color: Clear to milky white crystals. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

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

Identified July 5, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale. Color: Clear to milky white crystals. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Formed through the precipitation of minerals from hydrothermal fluids or groundwater into hollow cavities (gas bubbles in volcanic rock or sedimentary voids). Over millions of years, crystals grow inward toward the center of the cavity.

Uses & applications

Primarily used for decorative purposes, educational displays, geological collecting, and lapidary art. High-purity quartz is also used in electronics and glass-making.

Geological facts

The word geode comes from the Greek word 'Geoides' which means earth-like. Unlike a vug, which is a cavity in rock, a geode has a separate outer shell that is harder than the surrounding host rock.

Field identification & locations

Identify in the field by looking for rounded, hollow-feeling rocks with a bumpy, cauliflower-like exterior texture. Common in desert regions of Morocco, Mexico, and the Western United States. Collectors value geodes that remain intact or are cleanly halved.