Geode (Unopened)

Physical Properties

Hardness: 7 (Mohs scale), Color: Dull gray to tan exterior with a rough, bumpy texture, Luster: Earthy exterior, Crystal Structure: Hexagonal (interior crystals), Specific Gravity: 2.65

Formation & Geological History

Formed in the cavities of sedimentary or volcanic rocks. Over millions of years, mineral-rich water seeps through the porous shell, depositing crystals (usually quartz or calcite) on the interior walls.

Uses & Applications

Used primarily for collector specimens, interior decor, education, and lapidary work. Highly valued by hobbyists who enjoy cracking them open to reveal crystals.

Geological Facts

The word geode comes from the Greek word 'geoides,' meaning 'earth-like.' While they look like ordinary rocks on the outside, they can contain beautiful amethyst, citrine, or clear quartz inside.

Field Identification & Locations

Identify in the field by looking for unusually round or oval-shaped nodules that feel lighter than regular rocks of the same size. Commonly found in desert environments like the Southwestern US, Mexico, and Brazil.

Identified on: 4/30/2026

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