mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Clear to white; Luster: Vitreous to greasy; Crystal Structure: Trigonal (hexagonal prisms); Cleavage: Indistinct/Conchoidal; Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Clear to white
Luster: Vitreous to greasy

Identified June 30, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Clear to white; Luster: Vitreous to greasy; Crystal Structure: Trigonal (hexagonal prisms); Cleavage: Indistinct/Conchoidal; Gravity: 2.65

Formation & geological history

Formed in hollow cavities in sedimentary or volcanic rocks. Mineral-rich groundwater seeps into the cavity and precipitates crystals over long periods. Often found in Mississippian-age limestone beds.

Uses & applications

Primarily used as decorative display pieces, educational specimens, and in the lapidary arts. Historically, quartz has been used in electronics and glass-making.

Geological facts

The word geode comes from the Greek word 'Geoides' meaning earth-like. Unlike solid nodules, geodes are hollow, allowing crystals the space to grow inward.

Field identification & locations

Identify in the field by looking for rounded, bumpy, potato-like nodules that feel lighter than solid rocks of the same size. Commonly found in deserts or riverbeds in regions like Morocco, Mexico, and the US Midwest.