mineral

Quartz geode

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

AI-generated identification · may be incorrect

White to pale gray, vitreous-to-dull luster, fine sparkling crystals lining a cavity; quartz hardness Mohs 7, no cleavage, conchoidal fracture, specific gravity about 2.65. The outer rind appears gray chalcedony or weathered volcanic rock.

Identified September 8, 2026More mineral →

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Physical properties

Formation & geological history

Forms when gas cavities in volcanic lava are later lined by silica-rich groundwater; chalcedony precipitates first, followed by quartz crystals. Commonly Cenozoic to Paleozoic, depending on locality.

Uses & applications

Used as a decorative specimen, lapidary material, and source of small display crystals; generally ornamental rather than industrial in this form.

Geological facts

The cavity is a vug, and the tiny crystals are called drusy or druzy quartz. Colorless quartz may appear white because of microscopic inclusions, chalcedony, or surface weathering.

Field identification & locations

Identify by the hollow cavity, sparkly quartz lining, glassy crystal faces, and hardness sufficient to scratch ordinary glass. Common geode sources include Brazil, Uruguay, Mexico, Morocco, and the United States, especially Iowa, Kentucky, and Oregon.