mineral

Quartz Geode Fragment

Silicon Dioxide (SiO2) in a Sedimentary Host

Hardness: 7 (Mohs scale), Color: White/Gray/Translucent, Luster: Vitreous to dull, Crystal structure: Hexagonal/Trigonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific gravity: 2.65

Identified May 18, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: White/Gray/Translucent, Luster: Vitreous to dull, Crystal structure: Hexagonal/Trigonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific gravity: 2.65

Formation & geological history

Formed through precipitation of mineral-rich water within cavities of sedimentary or volcanic rocks. Usually found in limestone or volcanic ash beds dating from various geological eras.

Uses & applications

Primarily used for decorative purposes, educational teaching aids, and as affordable collector items.

Geological facts

Geodes are hollow, subspherical structures. The word 'geode' comes from the Greek word 'Geoides' meaning 'earth-like'. They act like time capsules, preserving the mineral growth that occurred millions of years ago.

Field identification & locations

Identify in the field by looking for lumpy, potato-like nodules that are lighter than solid rocks of similar size. Commonly found in desert regions of Morocco, Mexico, and the Midwestern USA (Keokuk area).

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