mineral

Quartz geode (likely druzy quartz in chalcedony)

Quartz, silicon dioxide (SiO₂), commonly with microcrystalline chalcedony

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent to white/gray, vitreous to sparkling druzy luster, with quartz crystals lining a cavity. Quartz is trigonal and has no cleavage; the tan exterior may be iron-stained host rock.

Identified August 26, 2026More mineral →

Explore Quartz geode (likely druzy quartz in chalcedony) in the encyclopedia →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater filled a cavity in volcanic rock, depositing chalcedony and later quartz crystals. Geodes commonly formed in Cenozoic volcanic flows, though the specimen’s exact age and locality cannot be determined from the image.

Uses & applications

Used as a decorative and collecting specimen; attractive druzy quartz is sometimes used in jewelry and ornamental objects. It has little construction value at this small size.

Geological facts

The sparkling surface consists of many tiny quartz crystal faces reflecting light. The hollow cavity and crystalline lining are characteristic of a geode rather than ordinary massive quartz.

Field identification & locations

Look for a rounded, weathered outer rind and an internal cavity lined with pointed or sugary quartz crystals; quartz should scratch glass but not be scratched by steel. Common sources include Brazil, Uruguay, Mexico, Morocco, and the United States.