metamorphic

Tumbled brown quartzite pebble

Quartzite, composed predominantly of microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness about 7 Mohs; brown to olive-brown, opaque, and glassy to waxy when polished. Massive, nonfoliated texture with no visible cleavage; specific gravity approximately 2.6–2.7.

Identified September 11, 2026More metamorphic →

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Physical properties

Hardness about 7 Mohs; brown to olive-brown, opaque, and glassy to waxy when polished. Massive, nonfoliated texture with no visible cleavage; specific gravity approximately 2.6–2.7.

Formation & geological history

Formed when quartz-rich sandstone was metamorphosed and recrystallized under heat and pressure, commonly during Precambrian to younger mountain-building events. The rounded shape and glossy surface indicate water abrasion followed by human tumbling/polishing.

Uses & applications

Used as durable aggregate, paving and building stone, landscaping rock, and decorative tumbled stone; generally not used as a gemstone except in ornamental pieces.

Geological facts

Quartzite commonly preserves few original sandstone textures because quartz grains fuse together, making it notably resistant to weathering. Its brown color may result from iron-oxide staining or minor incorporated minerals.

Field identification & locations

Identify it by its very hard, quartz-rich body, lack of layering or cleavage, and inability to scratch it with a steel knife; it should scratch ordinary glass. Common in river gravels and quartz-rich mountain belts.