metamorphic

Rounded quartz-rich pebble, likely quartzite

Quartzite (mostly crystalline quartz, SiO₂)

AI-generated identification · may be incorrect

Hardness about 7 Mohs; cream to tan with iron-oxide staining, waxy to vitreous luster, massive granular texture, and no obvious cleavage. The smooth shape indicates prolonged water or sediment abrasion; exact identification is limited by the photograph.

Identified September 19, 2026More metamorphic →

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Physical properties

Formation & geological history

Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure, recrystallizing the grains into an interlocking mass; ages range from Precambrian to younger mountain-building events. It commonly occurs in metamorphic belts and stream gravels derived from them.

Uses & applications

Used as crushed stone, aggregate, paving, building stone, and occasionally as a decorative or lapidary material. This specimen appears primarily suitable for collecting or polishing.

Geological facts

Quartzite is generally more resistant to weathering than sandstone and can form prominent ridges and durable river pebbles. Yellow-brown coloration commonly comes from limonite or hematite.

Field identification & locations

A glass-scratch test can support quartzite identification, though it may damage the specimen; it should not be scratched by a steel knife. Look for fused-looking quartz grains rather than loose sand grains or sedimentary layering.