mineral

Quartz geode

Quartz, silicon dioxide (SiO₂), likely a chalcedony-lined geode with drusy quartz crystals

AI-generated identification · may be incorrect

White to colorless, vitreous-to-sparkly luster; quartz is Mohs hardness 7, lacks cleavage, has hexagonal crystal structure, and specific gravity about 2.65. The rough exterior may be chalcedony or weathered host rock, while the cavity is coated with fine quartz crystals.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic or sedimentary host rock, depositing chalcedony and later quartz crystals. Individual geodes commonly formed millions to hundreds of millions of years ago, depending on locality.

Uses & applications

Used as decorative specimens, bookends, and lapidary material; attractive pieces may be used in jewelry or home décor.

Geological facts

The glittering surface is drusy quartz—many tiny crystal faces reflecting light. Quartz can develop from repeated episodes of cavity filling and crystal growth.

Field identification & locations

Identify by the hollow, rounded nodule and hard, glassy, sparkly crystals that do not scratch with a steel knife; acid fizz would suggest calcite rather than quartz. Common sources include Brazil, Uruguay, Mexico, and the United States.