mineral

Quartz geode (likely druzy quartz in chalcedony)

Quartz, SiO₂, with possible microcrystalline chalcedony host

AI-generated identification · may be incorrect

Gray-white, translucent to transparent drusy crystals with vitreous luster; quartz is Mohs hardness 7, has a hexagonal crystal structure and indistinct cleavage, and specific gravity about 2.65. The rough outer rind appears silica-rich and weathered.

Identified September 4, 2026More mineral →

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

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater deposited quartz crystals lining a cavity in volcanic or sedimentary rock, later cut open; exact geological age and locality cannot be determined from the image. The specimen may be natural or lightly sawn and polished on its display face.

Uses & applications

Used mainly as a decorative, educational, and collecting specimen; attractive quartz geodes may be used in jewelry or lapidary work, but this example appears more suitable for display.

Geological facts

The sparkling surface is caused by many tiny quartz crystal faces reflecting light. Gray coloration can result from inclusions, host-rock material, or minor iron and other impurities.

Field identification & locations

Identify by testing for hardness greater than glass, observing conchoidal fracture, and checking for quartz crystal faces; common sources include Brazil, Uruguay, Mexico, and Morocco. Do not confuse it with calcite, which is softer and reacts readily with acid.