mineral

Quartz Geode or Vuggy Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: tan to white outer rind with clear/smoky crystals, Luster: Vitreous to dull, Crystal structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture).

Identified July 9, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: tan to white outer rind with clear/smoky crystals, Luster: Vitreous to dull, Crystal structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through hydrothermal processes or silica-rich fluids filling cavities in volcanic or sedimentary rocks. This specimen appears to be a stream-tumbled mineral nodule that has been naturally weathered.

Uses & applications

Used primarily for educational specimens, lapidary work (polishing), and as a collectible for rockhounds.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. These specific specimens often start as hollow geodes but can become solid 'thundereggs' if the silica completely fills the cavity.

Field identification & locations

Identify in the field by looking for rounded, potato-like stones with a different texture or weight than surrounding rocks; often found in gravel pits or riverbeds. A broken surface reveals crystal centers.