mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Clear to white interior crystals with tan/beige exterior rind; Luster: Vitreous (glassy) crystals with dull matrix; Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: ~2.65

Hardness: 7 on Mohs scale
Luster: Vitreous (glassy) crystals with dull matrix

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed via secondary chemical precipitation within gas cavities (vesicles) in volcanic rocks or cavities in sedimentary rocks, such as limestone, as mineral-rich fluids flow through over thousands to millions of years.

Uses & applications

Popular as decorative display specimens, educational samples, lapidary art materials, and metaphysical crystals.

Geological facts

Geodes often look like ordinary, unremarkable rounded rocks on the outside, hiding sparkling crystal cavities within that are only revealed when cracked open or cut.

Field identification & locations

Identified by the hollow or partially hollow cavity lined with well-formed quartz crystals inside a tough, chalcedony or limestone matrix. Commonly found in locations like Morocco, Brazil, Mexico, and the Midwestern United States (Keokuk region).