mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: White to off-white/tan with yellowish iron staining; Luster: Vitreous to dull (exterior); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White to off-white/tan with yellowish iron staining
Luster: Vitreous to dull (exterior)

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral within cavities (vugs) created by gas bubbles in volcanic rock or hollows in sedimentary rock. Silica-rich groundwater percolates into the cavity, slowly depositing layers of crystals over hundreds of thousands to millions of years.

Uses & applications

Primarily used for interior decor, educational exhibits, and metaphysical collections. Industrial-grade quartz is used in electronics and glass manufacturing, though geode specimens are kept intact for aesthetic value.

Geological facts

Geodes are often indistinguishable from ordinary rocks on the outside, appearing as lumpy, round concretions. This specimen shows a 'botryoidal' or 'druzy' quartz habit where small crystals form a bumpy, grape-like surface.

Field identification & locations

Identify in the field by looking for round or egg-shaped nodules that feel lighter than regular rocks of the same size, which indicates a hollow center. Common locations include Brazil, Uruguay, Morocco, and the Midwestern United States (Keokuk region).