mineral

Quartz geode fragment

Microcrystalline and crystalline silica, SiO₂; likely quartz-lined chalcedony geode

AI-generated identification · may be incorrect

White to translucent drusy quartz crystals coat a rounded cavity, with dull granular chalcedony or weathered host material outside. Quartz is Mohs 7, glassy to dull luster, trigonal crystal structure, no cleavage, and specific gravity about 2.65.

Identified August 28, 2026More mineral →

Explore Quartz geode fragment in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Likely formed when silica-rich groundwater filled a gas bubble or cavity in volcanic rock, depositing chalcedony and later quartz crystals; the specimen’s precise geological age cannot be determined from the image. Common geode formation spans many millions of years.

Uses & applications

Used as a decorative or educational specimen and occasionally in jewelry or lapidary work; this small, rough fragment has modest commercial value.

Geological facts

The sparkling surface is drusy quartz—many tiny crystal faces reflecting light. The rounded exterior and hollow center are characteristic of a geode rather than massive quartz.

Field identification & locations

Common in basaltic volcanic terrains and sedimentary geode beds, especially Brazil, Uruguay, Mexico, and the U.S. Midwest. Confirm with a scratch test against glass and inspect for hexagonal quartz faces; avoid confusing calcite, which is softer and cleaves readily.