mineral

Quartz Geode / Druzy Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Pale yellow, light brown, tan, to off-white due to iron oxide staining. Luster: Vitreous to dull earthiness on the outer crust. Crystal structure: Trigonal (microcrystalline/druzy quartz aggregates). Cleavage: None. Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous to dull earthiness on the outer crust

Identified July 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities within sedimentary rocks (like limestone or shale) or volcanic rocks, where silica-rich hydrothermal fluids percolated over long periods and precipitated quartz crystals inward.

Uses & applications

Used primarily as decorative display specimens, lapidary material, gemstone carving, and popular mineral collection pieces.

Geological facts

Geodes often appear completely nondescript and rough on the outside like ordinary round stones, but contain brilliant sparkling crystal cavities inside or covered druzy surfaces.

Field identification & locations

Identified by its knobby, botryoidal, or bumpy crust topped with tiny sparkling quartz crystal points. Commonly found in sedimentary formations in the Midwestern United States (Iowa, Illinois, Missouri), Mexico, and Brazil.