metamorphic

Polished quartzite pebble (probable)

Quartzite; predominantly crystalline SiO₂

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale cream-gray, fine-grained, granular texture, and dull-to-satin luster. No visible cleavage; quartz grains are tightly interlocked, with specific gravity near 2.65.

Identified September 7, 2026More metamorphic →

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Physical properties

Hardness about 7 Mohs; pale cream-gray, fine-grained, granular texture, and dull-to-satin luster. No visible cleavage; quartz grains are tightly interlocked, with specific gravity near 2.65.

Formation & geological history

Formed when quartz-rich sandstone was metamorphosed under heat and pressure, commonly during Precambrian to Paleozoic mountain-building. Its rounded shape and smooth surface indicate river, beach, or human tumbling/polishing.

Uses & applications

Used as decorative stone, landscaping pebble, aggregate, and occasional cabochon or lapidary material. This common specimen usually has modest collecting value.

Geological facts

Quartzite is typically harder and more resistant to weathering than its sandstone precursor. A steel file or knife should not readily scratch it, while quartzite can scratch ordinary glass.

Field identification & locations

Identify by its sugary quartz texture, lack of obvious layering, and resistance to scratching; vinegar produces no reaction. Common sources include metamorphic belts worldwide, including the Appalachian, Rocky Mountain, and Scandinavian regions.