mineral

Quartz geode

Quartz (SiO₂), likely a chalcedony-lined geode with druzy quartz

AI-generated identification · may be incorrect

White to translucent gray druzy crystals line a hollow cavity, with a rough tan-gray outer rind. Quartz has Mohs hardness 7, vitreous luster, trigonal crystal structure, no cleavage, and specific gravity about 2.65.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater deposited chalcedony and later quartz crystals inside a gas cavity or hollow nodule, commonly in volcanic basalt; the specimen is likely Cenozoic or younger, though age cannot be determined from the image.

Uses & applications

Used as a decorative and collectible specimen, bookend, or jewelry component; geodes have little industrial value compared with massive quartz.

Geological facts

The sparkling surface consists of many tiny quartz crystals (“druzy”). Slightly yellow areas may be iron staining or a coating, and the cavity can make the specimen lighter than a solid quartz mass.

Field identification & locations

Identify by testing for glass-scratching hardness, observing glassy crystal sparkle, and checking that it lacks obvious cubic cleavage; common sources include Brazil, Uruguay, Mexico, and the United States.