mineral

Quartz Geode (River Cobble)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: White, tan, or clear crystals; Luster: Vitreous to waxy; Crystal structure: Hexagonal/Trigonal (microcrystalline or drusy); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White, tan, or clear crystals
Luster: Vitreous to waxy

Identified May 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed by mineral-rich groundwater precipitating silica into hollow cavities within sedimentary or volcanic host rocks. Often found as rounded nodules in riverbeds after the host rock has eroded away.

Uses & applications

Primary use for decorative display, crystal collecting, metaphysical purposes, and educational specimens.

Geological facts

Geodes are virtually indistinguishable from regular rocks on the outside until cracked open to reveal the crystal cavity within. This specimen shows a drusy quartz lining within a weathered sedimentary exterior.

Field identification & locations

Identify by looking for rounded, lumpy 'cauliflower' textures on the surface and a lighter-than-expected weight for its size. Commonly found in gravel bars of ancient riverbeds or limestone deposits.