sedimentary

Geode (Calcite or Quartz)

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Calcite) to 7 (Quartz); Color: White, cream, or brown; Luster: Vitreous to dull; Crystal structure: Trigonal or Hexagonal; Cleavage: Perfect rhombohedral (if calcite).

Hardness: 3 (Calcite) to 7 (Quartz)
Color: White, cream, or brown
Luster: Vitreous to dull

Identified June 17, 2026More sedimentary →

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Physical properties

Hardness: 3 (Calcite) to 7 (Quartz); Color: White, cream, or brown; Luster: Vitreous to dull; Crystal structure: Trigonal or Hexagonal; Cleavage: Perfect rhombohedral (if calcite).

Formation & geological history

Formed as secondary mineral precipitates within cavities (vesicles) of volcanic or sedimentary rocks. Over millions of years, mineral-rich groundwater seeps into these hollows and crystallizes.

Uses & applications

Primarily used as decorative display pieces, for geological education, and in the metaphysical/gemstone collecting market.

Geological facts

The word geode comes from the Greek 'geoides' meaning earth-like. While they look like ordinary rocks on the outside, their interior can contain complex crystal gardens.

Field identification & locations

Identify by its hollow center or rounded, lumpy 'cauliflower' exterior texture. Commonly found in desert regions or areas with limestone/volcanic ash beds.