mineral

Druzy quartz geode

Microcrystalline quartz (SiO₂), commonly lining a volcanic geode cavity

AI-generated identification · may be incorrect

Gray to blue-gray botryoidal/druzy quartz with a glassy to sparkling luster and irregular massive outer rind; quartz hardness is Mohs 7, with no cleavage and conchoidal fracture. The rounded interior growths are likely chalcedony or fine quartz crystals, possibly with minor iron or manganese staining.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills gas vesicles in volcanic rock, depositing chalcedony and quartz inward from the cavity walls. Individual geodes may form relatively soon after host-rock emplacement, commonly in Cenozoic or older volcanic flows.

Uses & applications

Used as a decorative specimen, cabochon, polished display stone, or lapidary material; it has modest jewelry value unless exceptionally colorful or crystalline.

Geological facts

The hollow cavity and inward-growing crystals are diagnostic of a geode. Druzy texture consists of countless tiny quartz crystals rather than a single large crystal.

Field identification & locations

Identify it by its hollow or partly hollow rounded cavity, sparkling quartz lining, and hard, nonmetallic surface; common sources include Brazil, Uruguay, Mexico, Morocco, and the United States. A steel file should not easily scratch quartz.