metamorphic

Quartzite pebble

Quartzite; predominantly microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale gray-white with rusty iron-oxide staining, dull to weakly vitreous luster, massive granular texture, and no obvious cleavage. The rounded, smooth shape indicates water transport or natural abrasion.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone recrystallized under heat and pressure, commonly during mountain-building; its exact geological age cannot be determined from the image. The specimen was likely weathered from a quartzite outcrop and rounded in a stream or on a beach.

Uses & applications

Used as crushed aggregate, road stone, railroad ballast, building stone, and decorative landscaping material; attractive pieces may be collected or polished. Ordinary pebbles have little commercial value.

Geological facts

Quartzite is more resistant to weathering than its parent sandstone and commonly forms durable ridges and boulders. Iron oxides produce the orange-brown surface patches.

Field identification & locations

Identify it by testing that it scratches glass and resists steel, has a sugary fused-quartz texture, and does not fizz with dilute hydrochloric acid. Common in river gravels and metamorphic mountain belts worldwide.