mineral

Quartz geode

Microcrystalline quartz (SiO₂), commonly with chalcedony and possible calcite inclusions

AI-generated identification · may be incorrect

White to pale-gray drusy quartz crystals line cavities within a tan, weathered host. Quartz has Mohs hardness 7, vitreous luster, trigonal crystal structure, no cleavage, and specific gravity about 2.65; the rough outer rind is likely silica-rich volcanic or sedimentary material.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed when mineral-rich groundwater deposited chalcedony and quartz crystals inside a gas cavity or hollow in rock. The precise geological age and host rock cannot be determined from the image; geodes form in volcanic flows and some sedimentary deposits.

Uses & applications

Used mainly as a decorative and educational specimen; attractive crystal-lined pieces are collected, displayed, or used in lapidary décor rather than construction.

Geological facts

The cavity formed first, then successive silica-rich fluids coated its walls; the tiny sparkling crystals are called drusy quartz.

Field identification & locations

Identify by a hollow or partially opened rounded rind covered internally with tightly packed quartz crystals, which scratch glass and do not fizz in dilute hydrochloric acid. Common sources include Brazil, Uruguay, Mexico, Morocco, and the United States.