metamorphic

Quartz-rich quartzite pebble

Quartzite (mostly SiO₂)

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale cream to white with tan weathering, vitreous to dull luster, granular interlocking quartz crystals, and no obvious cleavage. The elongated, water-worn shape indicates a rounded pebble rather than a crystal.

Identified September 18, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was metamorphosed under heat and pressure, commonly during mountain-building; its original age may range from Precambrian to younger, depending on source. Later erosion produced the rounded specimen and surrounding gravel.

Uses & applications

Used as durable aggregate, road stone, landscaping gravel, building stone, and occasionally decorative material; generally not gem quality.

Geological facts

Quartzite is tougher and more resistant to weathering than its sandstone precursor. A steel knife usually does not scratch it, while quartz or glass can scratch a steel knife.

Field identification & locations

Common in river gravels, glacial deposits, and metamorphic mountain belts worldwide; identify by its sugary quartz texture, lack of sandy grains or bedding, and hardness. The image alone cannot exclude pale granite, chert, or silicified rock.