mineral

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Hardness: 7 Mohs; Color: White/Colorless; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct/Conchoidal; SG: 2.65

Hardness: 7 Mohs
Color: White/Colorless
Luster: Vitreous to greasy

Identified June 11, 2026More mineral →

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Physical properties

Hardness: 7 Mohs; Color: White/Colorless; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct/Conchoidal; SG: 2.65

Formation & geological history

Formed from silica-rich hydrothermal fluids filling vugs or cavities in volcanic or sedimentary host rocks. As the fluids cool or evaporate, crystals precipitate inward from the cavity walls.

Uses & applications

Used in glass manufacturing, electronics (due to piezoelectricity), abrasive sandblasting, and as ornamental specimens or jewelry components.

Geological facts

Quartz is one of the most abundant minerals in Earth's crust. Geodes are often called 'thunder eggs' when they occur in volcanic ash layers.

Field identification & locations

Look for rounded nodules with a hollow or crystalline center. Can be identified by its ability to scratch glass and lack of reaction to acid. Common globally, especially in geodes from Morocco, Brazil, and the USA.