metamorphic

Quartz-rich metamorphic pebble, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with mica or feldspar

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale gray-green, granular and sugary crystalline texture, with a dull to weakly vitreous luster. Quartzite has no prominent cleavage, irregular fracture, and commonly feels notably hard and dense.

Identified September 2, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was deeply buried and recrystallized under heat and pressure, commonly during Precambrian to Paleozoic mountain-building. This rounded specimen was likely transported and weathered in a gravel deposit.

Uses & applications

Used as crushed aggregate, road stone, building stone, and decorative slabs; attractive pieces are collected, though this small weathered pebble has little commercial value.

Geological facts

Quartzite is harder and more resistant to weathering than its sandstone parent, so it commonly survives as durable stream or glacial gravel.

Field identification & locations

Identify it by its fused, sugary quartz texture and inability to scratch easily with a steel knife; unlike sandstone, grains are not readily rubbed away. Common in mountain belts and glacial deposits worldwide.