metamorphic

Tumbled brown aventurine (likely quartzite)

Quartz-rich quartzite, predominantly SiO₂; exact identification cannot be confirmed from the image alone

AI-generated identification · may be incorrect

Opaque, rounded brown-gray specimen with a fine sugary sparkle; quartz hardness about 7 Mohs, vitreous-to-dull luster, and no obvious cleavage. Quartz grains form a granular, interlocking texture; iron-oxide inclusions may cause the brown color.

Identified October 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when quartz-rich sandstone recrystallized under heat and pressure, then naturally rounded and polished by tumbling. Quartzite forms in many geological periods; its age cannot be determined visually.

Uses & applications

Commonly sold as a tumbled decorative stone or craft material; quartzite is also used as aggregate and dimension stone.

Geological facts

Aventurine is technically quartz or quartzite with reflective mineral inclusions; the pictured specimen’s subdued sparkle may instead be ordinary quartzite.

Field identification & locations

Look for a hard, quartz-rich surface that resists scratching by a steel knife, with granular texture and no fizz in dilute acid. Quartzite occurs worldwide; image identification is tentative.